artsunlimited SF wouldn’t have a clue if a title had burn-in subtitles, as, as others have said, that’s part of the picture, and given that SF doesn’t re-encode the video stream, SF has nothing to do with buringin-in forced subtitles. If it’s not burnt-in by the vendor’s process, it won’t be by SF.
Having said that, if you want to burn-in the forced subtitles yourself, you can do, but that requires re-encoding the video, try things like QSVEnc/VCEEnc/NVEnc depending on what encoding acceleration you have; but don’t expect help on using those on forums here.