Follow up question. What do we know about their life style? From what I see in what little photographs there are on the internet it seems like they were relatively sophisticated masons.
The problem here is that the Crimean goths are mentioned over 200 years ago, and nobody has ever found any of them left. This is common with the disappearance of an ethnic group and doesn't imply that any "event" caused their disappearance. Instead, the Crimean goths, like the many other groups of goths, assimilated with local populations.