Sorry for the double-post, but I found the solution to my problem, and I wanted a separate post to showcase the solution for others with this problem.
So, I found out why FEditor could not read text ID 0x054A in my FE7 hack… I sacrificed it to the Gods.
Following the “Use the Tactician name on a unit” documentation, I originally used 0x054A as the text ID for the Tactician’s name for a unit. However, I did not realize that FEditor would no longer recognize the ID. I could not access it, and I could not dump my ROM’s text past the ID. To fix this, I opened my ROM in a hex editor and went to the pointer of the text ID used (to find the pointer: type the text ID into a hex calculator, multiply by 4, and add the answer to B808AC {the base offset of the text table}). There, I found 18 BC 02 82, which is the pointer to the Tactician RAM data. I opened up a clean FE7 ROM in the hex editor, went to the same location as my text ID’s pointer, copied the first four bytes in that location, and paste-wrote it on top of the 18 BC 02 82. I saved my hack’s ROM to undo the Tactician’s name setup, and FEditor was able to access text ID 0x054A again. Now I can fully dump my ROM’s text.
Because I still need to use the Tactician’s name as a unit’s name, I decided to sacrifice text ID 0x133D instead. It’s the last ID in the original ROM and is only a song title for the Final Battle theme of the game (which is seen only in the music menu of the game anyway). This way, I can dump the text from my ROM hack with no issues. For those who wish to use the Tactician’s name for a unit, I recommend using this advice to minimize any issues with FEditor.
Thank you for your time, and thank you Solum and Primefusion for helping me with my problem.