it ends in defeat immediately upon start, because for some reason Omega isn't created? I dunno why...

If the player uses debug mode, they can skip certain events that the add-on's original author probably assumed would always fire. These events should be rewritten to account for the possibility that they might not happen when the original author intended them to.

It keeps showing as UNTLB range_snipe

See feedback from @Konrad22 on the forums: https://forums.wesnoth.org/viewtopic.php?p=675657#p675657

I have just played through S1 and I see there are some 17 villages, however the map only shows me like 10. 7 villages are missing some image.

I've added a bunch of new music tracks in recent-ish commits; I still need to actually use them, though...

Lots of scenarios do

[endlevel]
    result=continue
[/endlevel]

which is wrong and needs to be fixed.

I'm guessing it can probably be replaced with result=victory instead.

some images are missing or otherwise fail to display properly

Warning: Unit bdrone not found as advancement of 'binfantry'
Warning: Unit Omega advances to unit Omega in a loop.
Removing advancement Omega.
Warning: Unit Sporehealer advances to unit Xylash_Grub in a loop.
Removing advancement Xylash_Grub.
Warning: Unit Sporehealer advances to unit Brute in a loop.
Removing advancement Brute.
Warning: Unit Sporehealer advances to unit Consumer in a loop.
Removing advancement Consumer.
Warning: Unit Sporehealer advances to unit Scout in a loop.
Removing advancement Scout.
Warning: Unit Sporehealer advances to unit Sporesealer in a loop.
Removing advancement Sporesealer.
Warning: Unit Sporehealer advances to unit Antitank in a loop.
Removing advancement Antitank.
Warning: Unit Sporehealer advances to unit Xfighter in a loop.
Removing advancement Xfighter.
Warning: Unit Frigate advances to unit Frigate in a loop.
Removing advancement Frigate.
Warning: Unit bdrone not found.
Error: No attack icon 'attacks/Rifle.png' found for 'Fleet_Commander'.

https://units.wesnoth.org/1.16/The_War_of_Terrador/error.html

Should be Xfighter and not Fighter

The add-on looks like a buggy mess.

should be pretty easy, there's just a lot of them, so I'm not really feeling motivated to go through everything... just some menial busywork...

It's kinda too big to go thru as-is; I should probably split it up into separate subdirectories for each race. Of course, in doing so, I'll have to make sure I don't break any paths...