You can edit the rules in compfix.gml to add any missing functions or generally change code generation. Not sure if the replacer tool supports prefix operators - it’s a bit of a tricky topic and wasn’t needed for the original implementation (which was made for replacing variables like layer).
async_load is trickier - since GM creates it by itself, there’s not really much to replace. On one-off basis you could run qs_json_decode(json_encode(thing))