Well I'm sure they had higher level language dev environments that converted to ASM for production. (What I would give to take a look at one!) Could be the original code, or inefficiencies in their compilers.
I don't know if the dev tools extended as far back as the SNES or if it was just games (there are definitely dev tools for later systems) but might have had something in the gigaleaks.
Also for the gameboy but contemporary at least to the SNEShttps://www.pagetable.com/?p=28
All that said I have never seen devs talk about high level stuff for the SNES and whatnot. Indeed many talk* about how the PS1 and later N64 was a big shift in allowing C for the games themselves (with manglement also noting it as not having to hire greybeards and super turbo nerds that still know/would learn some assembly to use in anger). Some of the talk we have seen is about low level stuff, or indeed how music making types were also getting down and dirty with assembly, but I readily accept that "rule of cool" is in play for that one. Similarly disassemblies we have seen rarely have markers/fingerprints of compilers of the day, much less cross compilers** as that was still a distinction some made, and it would be years before all the people having real fun with compiler theory and giving us intrinsics and all the fun optimisations that might make such things less blindingly obvious. The leaked SDKs that have been around for years also go into serious depth with the hardware which if everybody had nice libraries (as they do on later systems, which we also saw correspondingly less useful info in) would be redundant at best.
*gdc talks ( https://www.youtube.com/watch?v=aMcJ1Jvtef0
), other conference talks, gamasutra has a bunch of stuff (not really relevant here but https://www.gamasutra.com/view/feature/131781/the_internet_sucks_or_what_i_.php
is one of my favourite articles), general interviews with games sites, ars technica "war stories", various developer commentaries (for the N64 but I really like conker king https://www.youtube.com/channel/UCbRUl7dkRVPKlYiUq4TmEaQ/videos
), especially about 10 years back when the indie devs rediscovered 2d gaming and classic styles such that the old hands still alive were dragged in to do things or teach people.
**Most consoles having chips used for "serious business" purposes, x86 having not quite won the battle yet, so having something there means there were some desires to have an actual compiler.