For a simple indicator, rewriting from scratch takes 2–4 hours. For a complex EA, 2 weeks. That is often faster than cleaning decompiled garbage.
: Hire a developer on a platform like MQL5.com to rewrite the logic from scratch based on the EA's behavior.
No GitHub magic wand. Don’t trust free decompilers; they’ll waste your time or harm your computer.
After manual fixes, try compiling. If successful, you now have a working (though messy) source code.