Okay I managed to reproduced the behavior in your screenshot, seems like it’s just something that occurs with certain dumps. I would just try out some different ROMs. I’ll try to figure out what causes this to happen, but in the meantime, obviously telling you where to find them illegal but I’ll provide the filenames of the dumps that did and didn’t work for me.
The one that worked was Fire_Emblem_-_Monshou_no_Nazo_Japan_Rev_1.sfc
The one that had this glitch was Fire Emblem - Monsyo no Nazo (V1.1) (J).fig
(which is weird, 'cuz that’s the one I initially tested it on and it was fine before… lol.)