There are two ways the patch might be distributed. Check the readme file included with the patch download.

Ensure your Super Robot Wars BX ROM is added to your game directory list.

Verify that the folder structure inside the mods directory strictly follows the romfs naming convention and contains the unpacked translation files rather than the zipped archive.

If the game boots in Japanese or crashes, verify the following common points of failure:

This is the recommended method if you patched the ROM on your PC into a single file.