Most of that is already addressed in the mod's Overview page.
Any mod that touches attachment or weapon stats will not be compatible with my mod, which massively changes how attachments and recoil works and balances all attachment and weapon stats already. In this case Freshte's mod is loaded first, so my mod will overwrite most of his changes so it's not as big of an issue, but I still recommend using one or the other instead of both.
You can no longer see the stat deltas by hovering over them because it causes much bigger performance issues than if they are disabled. It's the trade off to having a much more in-depth weapon modding system. Unfortunately there's nothing else I can do about it unless BSG optimizes their code.
In vanilla EFT, the stock AK-104 has 54 ergo. Your build would have 47. That's not fundamentally different to how it's balanced in my mod. You're comparing a gun with suppressor, scope, laser, and light to a gun without any that is 1.7kg lighter than it. If you were to take a stock AK-104 and add the same sight, laser/light and suppressor with a shitty handguard, no grip, stock pistol grip and stock, your build would have better ergo. The parts you put on that added ergo, like the stock, foregrip and pistolgrip, offset the negative ergo from the weight and balance. I fail to see how those mods made your build worse or how there was no point in adding them.
You can get your build a bit lighter by swapping some parts for lighter ones, and there are higher ergo foregrips, handguards and maybe stocks. You'll regain more ergo that way. You cannot go into a mod that rebalances attachments and weapons dramatically and expect the same builds or parts to be good, or for things to work the same.
Having said all that, as it is a test release, balance is not even close to being final. I'm constantly tweaking things. If you have any specific and constructive feedback as to what could be improved, please let me know.
At the same time, it will never be the case that a much heavier gun will have the same or better ergo than stock. That wouldn't make any sense, be balanced or be realistic IMO.