12+ players, 30+ characters - that’s my jam! That’s one of the best ways to play D&D, IME.
It might be wise, if you actually just want an answer to such a question, a) to only post the question, not the contextual example; b) to read, respond to, and internalize responses to the core question; c) to make posts summarizing these responses, rather than a “only solution a railroad GM will accept”-approved post of, “so are we all agreed that, in this case, we’re looking at X?”.
Senility willing, I’ll dig through this thread and re-post at least my own answers to the purported thread topic.