This is an 80% solution to PFW-1488 which should be somewhat compatible with the existing languages/translations infrastructure.
I don't see a point in extending the infrastructure a great deal to support some compile-time replacement in order to patch just MSG_DESC_FW_UPDATE_NEEDED.
Related PR: https://github.com/prusa3d/Prusa-Firmware/pull/3993
D.R.racer