Subtitle renaming
 

When BS Player download subtitles, could it rename the srt file EXACTLY after the video file without the name of the language at the end? Thanks

You can define format for downloaded subtitles in Preferences>Subtitles>Online subtitles>Save downloaded subtitles to>select Custom and define format.

For your case it should be %P\%F%SE or %P\Subs\%F%SE if you want subtitles to be saved to SUBS folder.