[fabianfred]

Any pre-existing missions made before the mod...should open normally with their brief readable too...
it is only after opening them in the FMB that a NEW _ru.properties file is produced.... so once you have finished editing....just delete the _ru.properties file....... if you have information there you do not want to lose...just delete the _ru...and leave the .properties in the file name

an easier way to change aircraft without this problem is to use the QMT Quick Mission Tuner utility.... links given elsewhere here....as that acts directly on the .mis file without opening the FMB