A couple things about this completely annoying and time consuming COLLECTION of games.
There is like 10 games or whatever. So asking for update of Halo Master Chief Collection means nothing. Maybe it's a specific game that is broken. It's better to request update of THAT.
The game has EAC, and you can run it WITHOUT EAC, but the point is that they don't want people to try and cheat ONLINE. Further they are locking down the achievements over and over. If you want to edit your achievements, go use the steam achievements unlocker, I don't have time to play games month after month with MICROSOFT who are mainly updating ONLINE and ANTI CHEATS in this series of games.
If your trainer is reporting .dll not found, you likely trying to activate the trainer BEFORE you are already in the game. Further if you play one game, then run another, the trainer won't still magically work, you have to close trainer then try again after it re loads. This is a stupid decision by the developers and a unique issue with this title. We have NO CONTROL OVER IT.
Regarding updating 10 games in perpetuity over and over and over, especially if they all are updating regularly and the entire registers being used completely change each patch, this would be an exercise in insanity and futility. I don't have the time to keep up with this series of games and it's insane patches and updates, which AGAIN are mostly updates for online and multiplayer and anti cheats, NOT the single player campaign.
This series is close to being just put on hold or retired completely. It's a never ending battle and I spend hours just REPLYING and posting the same thing over and over. Many issues are due to people not reading the instructions.
SO, with all this said, if you followed the instructions, waited until the game loaded BEFORE you try the trainer, and are using the correct trainer for the correct campaign, and are offline in single player mode, and launched the game without EAC, THEN you tried EACH option and one or more of them isn't working.. it would be great if you posted here THE GAME NAME (campaign) and which exactly options aren't working. Even then, it could take weeks to get throught them all, with more patches happening literally a day later. So no ETA, and I hope this explains more about this game. If there is more posts or more anger and more futility, it just may be that this series gets put down.
FYI,
Cal