Answer #1, yes the bolts fail.
Answer #2, no there is nothing stronger readily available and legal to install.
The L-19 Cessna part George mentioned is a modified AN7 bolt. Presumably, it has at least the same strength as an unmodified AN7. I wouldn't think it is stronger than a standard AN7.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
N7A '49 170A -More original than most making folks GREEN with envy
N42532 '45 J-3 Clipped Wing Cub