Granted, balance is a complex thing, but these changes indicate to me that DE has no coherent methodology to what they're doing with rivens and weapon balance in general. I would urge the team to calculate based on mathematical values and modify each based on weapon useability in challenging content rather than this 'nerf what is popular' strategy.
Arca Plasmor sticks out as a bad change, even with a riven it was never very good--its primary sin is being fun. It is an underdog killer weapon: It demolishes everything up to level 80 then falls off hard, so all you have done is weaken it in the content where it was already lacking, the content where the riven actually made a difference. That so few shotgun changes were made speaks to how perplexed you seem to be about how to handle the pellet/status calculation problem. I can tell you how I'd approach this: If a weapon is a status weapon like the Kohm make sure that it can hit its status threshold without a riven. The kohm is particularly stupidly balanced where there are two tiers of rivens even when you roll status. The difference between one over 120% and one below is monstrous in both power and flexibility. You should be internally designating which weapons are crit, status or raw then adjusting base stats accordingly so people can viably use their actual weapons of choice rather than being coralled into the use of a top-performing weapon which will then be nerfed under this, frankly ridiculous, 'nerf what is popular' regime. People use what they enjoy until it stops working, then they move on. If you look at the adjustment values it seems clear this popularity method is a failure with so many Sniper Rifles receiving nerfs despite their practical uselessness in any non-eidolon content and their nerf meaning practically nothing in relation to eidolons since we will still use them in the absense of viable alternatives.
No changes at all would have been superior to this unjustified, possibly unjustifiable, smorgasbord of random and largely superficial changes which will have to be revisited if we ever get any challenging content. What should be happening is serious analysis of content design both extant and slated to give meaningful choices to players. This really is frustrating to me, and I suspect to anyone who has an interest in actual balance and not the overarching riven market.
You have done a very bad job here. I hope now that you've dipped your toes you might dive in and make a real splash.