Twilight of the Arnor is really cool, and I really dig the new race specific tech trees. But, there are a couple of obvious flaws in the trees, many of which have been talked about before on the forums here.
I wanted to gather together all of the gaps, flaws and bugs in the tech trees into one place, partly so I could work out what was definitely a mistake and what was actually intentional, partly to help out people looking for information, and maybe to help the developers out too!
The issues at present, as I see them:
ISSUES
1) The following races lack the ability to research anything more than the basic Mining Starbase and Strabse Factory modules. This is because they no longer posess the Xeno Indistrial Theory chain of technologies, and the roughly equivalent replacements in each case do not provide starbase techs.
The Yor
The Thalan
The Iconians
The Korath (althought their cousins the Drengin DO get upgrades via an "Industial Starbase Construction" chain that seems to be unique to them)
SOLUTION: a) Give these civs access to the Drengin's "Indutrial Starbase Construction" branch
OR:

Give these civs the suitable upgrade as part of their branch which is equivalent to Xeno Indutrial Theory:
"Industrial Adaptation" for the Thalan, "Collective Manufacturing" for the Yor, "Industrial Replication" for the Iconians, and through the Slave Pits branch for the Korath(?)
2) The Thalan lack access to the Battle Stations Mk I starbase module (although they do have acces to Battle Stations Mark II and higher - it's just they can never upgrade to that point owing to the lack of Mark I).
SOLUTION: Give the Thalan access to this module with their "Defense Industries" tech.
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Now for the things where I'm not sure if they're errors or intentional...
3) The Torians, Krynn and Yor lack acces to Hyperwarp drives. Are they compensated for this in some way? (The Arceans lack acces to all drive tech beyond basic hyperdrive, but that I am pretty sure is intentional as they're compensated with their navigation tech).
4) The Thalan have no access to farms or any kind of food boosting building. This makes a certain degree of sense given their backstory, but it also seems kinda harsh.
That's it for now. Please post any other tech tree oddities, bugs, flaws or confusions you have to this thread!