So I'm not an RBY player, nor have I really played competitive mons for the last 5-6 years or something, but I feel like theres one option here that people aren't really considering, albeit a pretty controversial one. Revert back to pre-Crystal_ RBY?
Smogon, understandably, wants to keep its rulesets applicable to both simulator and cartridge play. This is particularly important when it comes to the most recent generation, as beyond SPL and WCoP there are thousands of people using Smogon rules for USUM + ORAS WiFi battles on cartridge. If you were to implement a rule or ban that is simply impossible to mimic on cartridge then you alienate a huge proportion of the community. However, when it comes to past gens (especially anything that now has a later-gen remake), do we really have a need to cater for the cartridge community? Are there any serious competitive RBY players battling on cartridge these days?
When Crystal_ discovered the various errors that we were incorrectly simulating in RBY, we felt an obligation to immediately integrate them. After all, we simulate Pokemon, which directly means that anything we do on simulator needs to also be possible on cartridge. However, in this case, the Smogon RBY community are the only people affected by effectively using a Simulator-exclusive set of rules. Yes, there will be people who don't follow Smogon at all who stumble across PS! and might want to play some RBY games with their friends, but I highly doubt these people will care whether or not its specifically true to the RBY experience on cartridge anyway - 99% true is definitely good enough for the nostalgia to shine through.
We were simulating RBY incorrectly for how long, 15 years? And either nobody until Crystal_ noticed, or just nobody seemed to care about it until that post. Again, I don't play RBY so feel free to shut me down if I'm wrong in saying this, but it feels like the community can quite widely agree that competitive RBY was "better" before things like the Body Slam mechanic were fixed. If you guys can come to a supermajority vote that 2014 RBY was better than what you have now, then I personally feel as though you'd be justified in basically undoing those changes. Call it RBY* or RBYlegacy or RBY2014 or something better than that if you aren't comfortable calling it RBY.
At an extreme end it seems like you're choosing between this:
1) Continue on with true RBY rules - the hardcore playerbase doesn't seem to enjoy it as much, perceptions of the format from other Smogon users has tanked, it is potentially just dying. The win in this situation is that you can remain proud that the game you are playing IS Pokemon through-and-through, and if somebody wanted to pick up a copy of Pokemon Yellow tomorrow and play Smogon rules, they could.
2) Revert back to 2014 RBY. It seems like this was a more enjoyable format for most, more "competitive"? Perceptions of RBY were better from other Smogon users, at least when I was still playing DPP/BW there was a significant amount of respect for the RBY community and the metagame. The downside is that Smogon RBY becomes less accessible and you can no longer play the Smogon format on cartridge, but I would argue that nobody is trying to do that anyway. Although controversial, this decision may act to prolong the life of RBY and the happiness of its playerbase.
People are inevitably going to be very strongly against changing cartridge mechanics and for good reason, but we've already set a precedent:
Sleep Clause - Doesn't actually exist in RBY, GSC, ADV, DPP, BW2 - it only exists in Stadium, Stadium2, Colloseum, Battle Revolution which are NOT the simulated formats. We've mashed rulesets together to make something cohesive. The only way to make Sleep Clause work on cartridge is to say "if you use a Sleep move again you forfeit" whereas on PS! the move will instead fail. This makes changes to the way PP stalling works, and in later gens, is relevant when it comes to Choice items. If you Sleep something in Gen4-7 with choiced Spore, you MUST switch on cartridge, but on simulator you can stay in and allow the move to fail.
Freeze Clause - as above.
Bugged moves - Not sure if this is the case still, but at least for a while the move Sky Drop did not work on PS!. BW was not a true simulation of cartidge at the time and nobody cared in the slightest. I am sure there are more examples of this.
There will be the "slippery slope" arguments too but I think this is pretty clearly a particularly a one-off situation. We were playing RBY wrong for years and a lot of people prefered playing it wrong compared to the real mechanics that we have now. We aren't picking and choosing mechanics to alter at a whim, but rather saying "hey that bugged set of rules was actually really fun and defined how we played RBY for 15 years, lets go back to that". The only other time this has happened off the top of my head was when we worked out that our ADV Spikes damage was incorrect, but comparatively thats a relatively minute detail. The other major difference compared to making artificial changes in other gens is that would affect practically nobody but the active RBY community.
Sorry for the super long post, will shut up now but tl;dr don't be overly attached to the idea of perfectly simulating RBY if the format ends up dying because of it. Is it better to truly simulate RBY if nobody wants to play it, or get it a little bit wrong but have the community actually enjoy it?