Ok, since this particular event is nearly over I figured now would be a decent time to give some feedback.
I think the most important thing you need to do is Show how much time is left for each Act. I know this was a experimental first and you weren't sure how long it would last, but I've seen lots of post here and on the wiki asking how much time was left and if they had enough time to hit rank 30. About a week ago I saw a post saying it'd last until at least the 15th which is good to know, but that needs to be in the game, not some post on the forum that most players would never read. Put the earliest end date on the nightwave screen, and if you decide to extend the date you can change there too.
Another thing I think needs changing is Show all the buy-able items instead of randomly cycling them. This really pissed me off at one point. Two deco helms I didn't have showed up one week. I only had enough credits to buy one before the end of the week, and with the long gap between credit rewards, no chance to get more. Will it come back before the end of this event removes all my credits? Who knows? If I remember right, one of your goals was to let players choose what type of reward they wanted/thought was most important, and you really can't choose if you don't know what is available because most of it is locked behind a RNG gate.
Third thing isn't completely specific to Nightwave. Add a "Hide Crafted" option to go with the "Hide Owned" option. It'd just making sorting through some of the "very" long lists easier and help avoid mistakes of not noticing the little "crafted" marker and buying a second copy of something (which I have done).
Fourth thing is the "Do XXXX with a friend or guildmate." While they're not that bad, I'm not a big fan of them, mainly because I'm a fairly introverted person who only has a couple of friends who play this game and only one of them would be able to do the harder mission this restriction gets put on.
Final main point is the Wolf himself. I know you wanted to make a cool challenging enemy, but most of the challenge seems to be he's incredibly bullet spongey, and his invulnerable friends like chucking area of effect DoTs that do a lot of damage (yes, it's been lowered to a more reasonable amount at the end, but that's only the last couple of days of the event). I'm sorry, but bullet spongey isn't challenging it's just tedious. I don't really have any advice on how to make something cool and challenging, but when I can (depending how i'm geared) unload literally all of my ammo for all my weapons into a mid level enemy and take away 1/3 of his HP that's just bad. As a side note, I know you've (finally) given us a couple of missions where the wolf is guaranteed so we can finish grinding out his drops (which is good, thank you). But putting rewards behind multiple layers of RNG is just bad. I spent nine hours (with an average mission time of ~2 minutes (with load time) to finally get all his drops. That would have been flat impossible when over the whole course of this event I've seen him about 14 times (a couple of which he bugged out and disappeared).
There's been a lot of talking about how slow credits come, how expensive some of the stuff is, and so on. I kinda see both ways with this. Can't make it too fast/easy to get stuff, but getting credits every couple of weeks seems a bit too slow. Not sure how to solve that, but it probably needs some tinkering.
I'm also a little disappointed by how little there is to do with the Nightwave. I usually get all the Nightwave missions done in a day or two, leaving me with one mission a day for the rest of the week.
Finally, why remove the secondary objectives in missions? Sure the exp they give is tiny, and there's only a handful of them, and they were simply, but it was still something to encourage me to break up the monotony a bit by changing up weapons or whatever while running a mission for the God-knows-how-manyth time.
All put, it's a decent start and I'm hoping you all can build it up into something really good. And I wanted to say "Thank You" to DE. Sure, you make design decisions that make me question your sanity, there are tons of bugs, and you rely way too much on grindy and RNG to retain players and extend play time, but you've made a game I (and many others) love and have put thousands of hours into over the last 5 years, and it can be really easy to lose sight of that with so many complaints from the community.