Since we only rely on awaiting a promise once, and all other differences between the scripts are just function identifiers, we can check for the version of GreaseMonkey at runtime, choose the correct functions and wrap the one async call in an if statement. These 15 or lines of code mean I don't have to maintain two scripts anymore.
The script also checks to see if you have the wrong version of bantflags for your userscript manager. Some general improvements to posting flags on 4chan.
Technically breaking changes for GreaseMonkey version 1.x hence the minor version bump but I don't think anyone actually still uses it and the script is built on features that because standard in browsers after GM 2.