If you need source code from an EX4, here are your only safe and legal options:
Files claiming "ex4 to mq4 v40427" were uploaded to VirusTotal and ANY.RUN. Results:
EX4 to MQ4 v4.0.427.1 decompiler is a legacy tool widely discussed in the trading community for its ability to reverse-engineer older MetaTrader 4 (MT4) executable files back into readable source code. The Role of EX4 and MQ4 Files
No legitimate, fully working decompiler exists for modern MT4 builds (since around build 600+). Old tools might claim compatibility but fail or produce broken, unrecoverable code.