Sep 8, 7:33am
It all depends on which events they would want to focus, but in my opinion, it would be possible to make quite faithful adaptation on Tolkien material and yet avoid various pitfalls in form of conflicting versions. One primary example, the UT section dealing with origin of Elessar, the green jewel, there are various versions of it's origin conflicting with each other and one contains a memorable conversation of Galadriel and Celebrimbor (in general History of Celeborn and Galadriel contains conflicting verisons, but First Age stuff is already off-limits so the events before would not need to be addressed much), the conversation of those two is a wonderful piece of Tolkien written dialogue, and in a show which bases on text with not nearly enough dialogue for such a show, they would do better to use this properly. It's also beneficial from storytelling perspective. That conversation is also the one reference in which it's said that Celebrimbor was in unrequitted love with Galadriel (who was already married to Celeborn and had a daughter). Elessar the stone is less important, as it never appeared in movies before in any case (while Lotr book has it even if unexplained origin). It would be better for dramatic purposes, adding some emotional conflict in the show with Celebrimbor of sorts.
Lore 'disrepancies' and adaptation
Other things such as Amdir also being called Malgalad in another text and Amdir said to be father of Amroth (while in some version he was supposed to be son of Celeborn and Galadriel) could also be easily resolved, either choosing one over other name or using both. Also Amroth connection to Galadriel could be explained, as being a friend who visited Eregion (Galadriel is said to have taken interest in Lorinand realm, and later travelled there through Moria with her daughter and Amroth as Unfinished Tales tell us, Celeborn stayed behind).
The Tar-Minastir and Tar-Telperien situation could be actually very well devised as you said, show the Minastir convincing the queen to intervene (as Minastir is all credited for it) and show this through fleshing out/inventing a scene in which in the court of Numenor messanger of Gil-galad arrives (as UT say, he send messages to Numenor for help when Sauron invaded, Elrond and Celeborn were fighting losing battle against Sauron's troops), and political debate happens after all Minastir as heir would sit in the Council of Sceptre) then have use of the character, admiral Ciryatur (the one who commanded the navy send to Middle-earth to help in the war) to be interacting with various elven characters throughout the war. Great battle of Gwathlo in which numenorean expedition succeeds in defeating Sauron would be highly cinematic moment, a massive War of the Elves and Sauron in overall would be amazing to put on screen, and UT give proper account of the events, down to the movements of troops and tactical decisions. Elrond and Celeborn and Gil-galad take very active part in it so it would beg to focus on them in the show over that course of events.
Of course in the end it all, again comes down to specific texts they will be able to use (it would seem that UT is largely responsible for the existence of the last map Amazon posted, Numenor map and the information on forests of the Enedwaith and Minhiriath are all there which indicates licensing rights allow for that), rest of the material is rather straightforward. The 'original inventions' are of course the problem then, which things will fit, but I guess Tolkien Estate veto right and presence of Shippey could alleviate such problems. I'm hoping they won't start suddenly making an awful lot of changes like PJ did to Hobbit, those went way too far for me.
Some things, as I said, would be based on canon but would have to be 'fleshed out' meaning Amazon writers would have to add detail to it (and for example that would be depicting Aldarion's meeting with Galadriel and Celeborn, mentioned in Mariner's Wife, that is if they will adapt this narrative at all, which I would beg them to do actually, it's the fullest narrative they can hope for, full of characters, character archs and dialogues all set out by Tolkien, we don't know what they talked about in this meeting, we only know that Aldarion went up river Gwathlo and somewhere near Tharbad had a meeting with them, as they lived in Eregion close by, here Amazon team would invent the dialogue from scratch).
Elros as a whole is for storytelling purposes less suitable character to appear for extended period of time, as Elros basically did nothing of note once he became king. I would say, again, that the best approach would be to adapt Mariner's Wife and in the same time show things happening around in Eregion, long before Sauron arrives there in fair form, showing the set-up so to speak, the family drama in Numenor could go on with focus on Aldarion, and through him showing events in Middle-earth, his contacts with Gil-galad, building first outpost the Vinyalonde, meeting with Galadriel and Celeborn when he sailed up river Gwathlo, (Aldarion's daughter Ancalime was alive and was queen during the time when Sauron personally arrived in Eregion in the years 1200 SA) the next thing would be Sauron's stay at Eregion, teaching the Elves how to forge rings, with Galadriel and Celeborn, and Gil-galad highly suspicious about this nice cool fellow Annatar, this would be heavily focused on Celebrimbor story arch and then it would lead to war (in Numenor several new generations would pass, Tar-Telperien the queen, Minastir as young prince, admiral Ciryatur, when war erupts as Sauron invades Eriador, Celebrimbor is killed, Elrond and Celeborn fight his troops as related in UT sections, Gil-galad sends messages for help to Numenor), events such as founding of Numenor could be sort of told as a tale, passed down among generations, some background to give context for the story at hand.
I guess there could be some sort of prologue kind of thing like the one Galadriel does in Fellowship movie, a very brief explanation for what is Numenor, how this civilization came to be and it's connection to other things, a proper context for the 'why's and how's' of Second Age. Elros is quite historically important, even if the character itself would not suit well for the drama show as he was basically living in peace and prosperity after he became appointed king of Numenor, he is important not only because all kings of Numenor are from his line of descendants, but also because of the influence of his actions, he is the founder of Armenelos and 'citadel of Elros' (which is basically a key location not unlike Red Keep from Game of Thrones, the main seat of power for Numenor, we will probably see this citadel a lot).
Elros and his father Earendil, who is almost a 'messianic' figure of Middle-earth would be historical context for later events. Kings of Numenor prided themselves for being 'Earendil's heir'. About Earendil we hear back in Lotr (even the movies) with reference to Earendil star being most beloved by the Elves, so the cultural impact of this character in-universe is enormous and Elrond Half-elven is also son of Earendil. Some explanation on who he was (and so also his son Elros), a legendary hero in it's own setting would be nice, especially if the events leading to Downfall of Numenor will be shown with Amandil trying to do what Earendil did those thousands of years ago.