Sorry, it's taken me a while to respond, but I'm going to look into adding this as a category very soon, so expect a definitive yes or no as to whether we will add this at some point today.
After checking it out a bit, I don't see how a crystal caverns speedrun would be much different, or much shorter than a normal one keystone speedrun. However, if you would like to speedrun it, then I don see any reason against adding it. So, if you would like to speedrun Crystal Caverns then link a video either here in this forum, or send me a dm, and Ill add it as a category. The speedrun would start in the same spot as a normal one keystone run (as soon as you select a first name), and end as soon as the "Victory (crystal caverns completed)" screen comes up.
After a large game changing update to prodigy, I am splitting the categories to New and Old version. From now on please submit runs ONLY to the new version