Deeply-nested clozes require exponential amounts of computation (= hangs), and a library we depend on also has a hard limit on nesting depth, so it’s not feasible to support arbitrarily-deep nesting I’m afraid. The best we could do is increase the limit we’ve imposed a little, which might make existing users happier, but means future users who are trying to use cloze deletions for incremental reveal are more likely to invest more heavily in them before discovering the computational runaway or hard limits of the library.