The only way I know to obtain a working trade patch is disassembly the clean cia, replace the rom and reassembly the cia.
I did it for italian versions and worked. For crystal I had to rewrite the original checksum (updated otherwise in a lot of emulators the game couldn't boot) or otherwise the mistery gift worked glitched.
If you downloaded an US version of the CIA already patched, perhaps they did it simply using a tool to pack a new CIA from a GBC rom. But in this way the trades will not work. You need ot unpack the original CIA, go in the folder including an odd file by 2 megabytes like the rom, copy the name, paste on patched rom (or use the IPS file directly to that file) and repack it. Should works then, like for me that I did it for italian Gold, Silver and Crystal, and all 3 roms worked.