Is there any limit to the depth? I've got it at 5 deep now and it seems to be working fine.
The boolean stack, which is 32. That's very hard.
That's NESTING level, not NUMBER OF BRANCHES. The Number of branches I guess is limited to ~255 rows in a single ladder rung, the maximum rung height.
It's hard to get a rung that deep, even using just "simple" STR/ANDSTR/ORSTR, let alone this (DUPBOOL/POPBOOL)