I'm playing as dumbass captain and he wants to build luxury spa which is quite a huge building. Do i need to build it on any base or only the main base counts?
Building it anywhere is fine. The check the game does for having a specific building only considers if you have one at all, it doesn't care where the building is located. I would recommend building it somewhere that has decent manufacturing capacity since you can use the luxury spa to upgrade courtesans and gladiatrixes into exotic dancers later on, but it's not necessary.
I am amused by the idea of having all of the CBT training facilities scattered across the world and the captain having to constantly fly between different continents to get all of her training done.
Can someone please tell me what's wrong with my ammo mod?
I think the issue is that you haven't declared that your edit is to the items: category in the rulesets. I've put that in and it now works on my end. I've attached it below.
Also, some advice. It's not good practice to copy over the entire entry for an item into a submod if you're only changing part of it. It adds bloat, hurts compatibility and most importantly, makes it harder to remember what exactly you changed.