So I approached this in a bit of an unorthodox way. I built its SSE version (with the swimmable Great Bay, its alternate song, and the original SSE Jungle options; plus a set of custom portraits) into an ISO with the then-most recent Minus Max beta (0.60) and an input lag fix codeset, for use with a USB loader and external HDD. I used a separate custom save slot so it created a new, empty save file upon first booting. In spite of a lot of potential conflict and basically zero know-how on my part, everything has worked more or less perfectly and in tandem. There are a few issues with odd typographical glitches in menus (improper characters, misaligned option names, and the like), stage icons (a couple of the CEP icons duplicated and overwrote Minus Max or original Brawl ones, though these overwritten icons still lead to their proper stages), and stage elements (speed caps seem non-existent in very specific cases, such as enemies in the Mario Bros. stage), but none of this is significant enough to affect play.

I'm being so thoroughly descriptive because the one exceptional problem I do have seems too solitary to have resulted from my bizarre method of implementing CEP without there being equally severe problems elsewhere (which there aren't). On Brinstar Depths, the entire stage rotates at an absolutely unplayable speed, to the point that it instantaneously kills all players in a match by tossing them unstoppably into the stage limits. If I had to guess, I'd say this is related to the same issue that removes speed caps on a scant amount of other stage elements, but I don't have near enough wherewithal to troubleshoot what that issue might be. I honestly just got lucky in combining tutorials across the various things I poured into this ISO, and so have little useful knowledge when it comes to the ins and outs of Brawl hacking.

I scoured online as thoroughly as possible and noticed no mention of a similar problem with this specific custom stage, outside of one passing mention earlier in this thread that had no response. I figured going to the horse's mouth was my best bet to try narrowing down the cause of this, even if it's potentially an as-yet uncommonly encountered problem. It'd be a shame if I couldn't get this reconciled, since that was always one of my favorite stages for those times when you just don't give a rat's arse about competitiveness.