I don't want to name "localization" in this one, but the German language part still hurts. One simple example, the remote mine. It is called "Fernmiene" in your localization. In theory not a bad approach, but there are several meanings and 2 spellings to that word ("Mine" / "Miene"). The spelling "Miene" only refers to facial expressions. Every other meaning is connected to the spelling "Mine". Including the intended one. So it should be "Fernmine", "Fernzündmine", "Mine mit Fernzünder" or whatever. This is eye-cancer. I'm playing this game in English to avoid this. Yes, improvements have been made, I see this, too. But there is still a remotely detonable facial expression in the game. And it sucks.
As far as I heard, the multiplayer Void Crusade is about to come, so I can check this off my list.
Multiplayer ... anything else is still on, though. The whole story part is delightful for some, annoying to others. Doing it together could take away a great part of the annoyance it means to some. First of all, please make the tank / Imperial Knight battles optional to play. It is a very nice thought, yes. But it is very time-consuming and non-rewarding. Plus, as far as I understand it, you can't make it work for multiplayer.
Which leads me to my next part. It might be a useful addition to implement a "brief campaign" version. Some people don't like it, but you need it for morality points, why don't you just make an option to have a way shorter campaign? The missing content could be a video summary or something. So that players may only play the important parts, maybe make the morality decisions, that kind of gist.
As somebody pointed out already, the Splinter Fleet event is nice, but not necessary. Think of it: Why would we play it? With the season still going on - which I recently finished, insert applause here - and void crusades or even just intel missions, what is my benefit of playing Splinter Fleet? Well, if I find an Ancient Relic with something like "kill 750 Tyranid enemies", I'll happily join the forces and hunt some down. But apart from that, there is just no reason. Nothing special I can only get there. Not even a freaking leader board. It just has nothing to make it worth my effort. Tyranids can be very nasty enemies, by the way. I'd rather slay myself some demon hordes than go against those ... abominations.
Sandbox elements. This is just a vague thought of mine. But there might be a possibility to implement things that players can build up. Well, like the cabal, I'll give you that. But maybe there's room for more.
I think you're already doing it, but ... I also want the "rest". Tzeench, Slanesh, I wants them. I needs them. Going up in flames, that is.
May you all always choose the one and true path of Puritanism.
The Emperor protects!