oh wow, really? i don't have a mac so this is good to know... not sure how i would go about testing to solve this, seems like a ren'py-side issue so hmmm..... thanks for reporting it.
I found that running
xattr -d -r com.apple.quarantine /path/to/Syrup2-folder/Syrup2.app
in the terminal fixes the issue, so it's probably an Apple Gatekeeper issue (I hate that thing)
