Black Star Games,
Along with the bare flag_alchemy that
TheeChaste is talking about, you're also trying to jump to a label that doesn't exist.
Flag_alchemy is referenced in multiple scripts, I'm assuming it should be flag_alchemy_1, but it's difficult to be sure.
ScriptError: could not find label 'rain_locked'.
Rain locked is just referenced in basement.rpy
If you're not already using an editor like notepad++, I strongly recommend it so when you change a flag you can search out the old version and be sure you've found them all to change them elsewhere.