Now I feel silly for having missed it! Thank you anyway!
Option to disable friendly fire
Yeah, it's the original game and American Revolt Not surprisingly, there is no option to select AR in Freesynd, but maybe some day ;) I think I made the mistake of configuring test_data in freesynd.ini, because with user.conf it does behave as expected. I think this issue can be closed after all. I have these files and the game starts when I realized to configure it in the right place: 6e7def4f2a10f238da138af2bcb2dfba6ea7e632 original_data.crc 6e7def4f2a10f238da138af2bcb2dfba6ea7e632 original_data.crc.bkp...
Had to recreate CRC32 (Syndicate Plus data)