If the triggers are made buffer local they would not clear global mappings, which would be available after snippet expansion, and it would clear the local mappings on other buffers, so it would help more that the built-ins.

But I agree that it would be better to save and restore the mappings - I didn't include it because I thought it would complicate a feature that would be used by too few users.

Maybe `mapcheck()` in VimL can be used.