If you enable MMU logging (mmu_common.h and cpummu030.h) and check the
log, do you see bus error from address that ends to FFC before it
crashes? (la=c0007ffc etc, it also probably have "ffff ILLEGAL._" at the
end of line which means prefetch bus error)
If yes, below patch improved prefetch handling after branch to address
space that generates bus error. Previously it partially reloaded already
prefetched data after RTE, now it does not but it seems there is some
bug or MMUSR flags are not right in this situation.
I tried few different Amiga Linux variants (some ancient Debian) and one
of them does not crash but generates unexpected line-F because of above
prefetch fault.