Hi, I have tried your mod and my overall feel is that it's... overwhelming. There's simply too much, too soon, too fast. On my first try, within 5 days I got invaded by someone, I have no idea who attacked my base because I haven't managed to kill a single enemy, despite sacrificing archon, 5 dogs and literally using ALL the ammo within base. I had to get creative with savegames to manage that. Not my proudest moment, but I was trying to see how everything works. Yes, I am playing at superhuman, BUT tactics mean nothing when I use all my ammo on a single alien and he doesn't even get a scratch.
Also, in my opinion, most of the things in the beginning are, well, useless. There's so much of it and cool looking, but i feel it's meaningless since I won't be using it. There's far too many planes, most of them I won't ever touch. Sure, it's nice to have all the russian jets, all the american squad or all EU shtick, but I feel it's not needed.
On the missions I got in the beginning, I felt 95% of weapons that could be purchased, while looking quite good, were less than useless. As far as I could see, weapons are too heavy for rookies to properly carry. I feel there's rather strong imbalance between weapon weights and ammo weights e.g. ZVI falcon ammo weighs 30, while loaded weapon weighs 15. So, with strength around 27 rookies cannot even carry a single rifle and a spare clip without loosing TU. Also, I believe incorporating weight equipped/str indicator would be very helpful.
Next, on many menus I found they did not have proper labels, rather STRING_XYZ placeholders. Not a biggie, but slightly detracts from experience. What I found frustrating is that ammos were all over the purchase screen. For example G36 clip was several weapons down, not under its' propre place, marksman rifle didn't have any clips attached to (it was under HMG) it and so on.
A minor irritation I found was that in the beginning, my planes were not fueled. As soon as I tried to intercept UFO, I had to return to base, same with skyranger. Also, nowhere could I find weapons to fit on some of the planes. I presume that I could research new weapons, but never got around to it.
I feel UFOpedia could be better organized. For example, there are STORY SO FAR chapters, but they are not placed in any meaningful order. Perhaps instead of labeling them as STORY SO FAR CHAPTER 1 better way would be STORY SO FAR CHAPTER 01 (or 001, depending on number of chapters). This way sorting algorithm will not make a mistake and put CHAPTER 11, 12... after chapter 1. Also, I somewhat struggled with the meaning of ufopedia entries, I believe english is not your primary language? I hope I'm not offensive and it's not my intention to offend, but I believe I could help you out with writing, if you're interested.
I applaude your effort and I really feel there's a lot of potential here, it just needs a bit more shine and balancing.