Hi!
Well, I have some minor troubles with this mod. I started it on OXCE 3.7x not on "conventional" OXC.
1.: Since the very beginning I have research options for "Floater medic", "Sectoid medic" and Snakeman. All got researched almost instantly (5-8 hours in game time) and either give me a free "live alien report" or crash to desktop (STR_WHATEVER not defined, last time it was the Megaworm\Multiworm)...
2.: When I try to launch one of my crafts the game crashes and say interface elements are missing. I could not got any ground combat or air combat as it just crash when I click on the "Interception" menu.
I downloaded the last valid 7z file from this mod and overwritten the old game folder with it. I not think it is a ruleset error as I always delete old rulesets before override a mod's folder just for sure...
Strange. I will look into it this weekend.
I'm currently using OXCE 5.1 (v2018-10-14) on my pc to test the mod, so in the meantime you can try to update to that version (or a newer one), because the version 3.7 is probably obsolete for the current release (0.4) of the mod.
Also the mod never used "OXCE" but it used "OXCE+"; they now have merged into one single project, so the difference does not exist anymore, but for your version 3.7 the difference still existed.