Since most mappers are players themselves who strive to improve in their gametype of choice and to have more fun maps to play on, getting more mappers and modders would mean getting more experienced players. CTB players should try to make the game type more attractive for standard/taiko players to try out.
At least from personal experience, I can say CTB didn't look very interesting until I discovered the existence of Reds. If there were more low-level CTB guest-diffs for mapsets that have jumps patterns and maybe a few Reds I think it would help attract std/taiko players to try out more CTB, which would lead to more mappers/modders in the long term. Or in short, even if you're not making full CTB mapsets right now, make CTB guest diffs. All of the taiko guest diffs is pretty much what led to the demand of taiko mapsets today.