Well, I finally found out what those values in the STRG block mean - they are part of a data structure that connects the STRG blocks to the sound names. Unfortunately, this data structure seems a little too complex to modify through pure hex editing. At the least, I lack the knowledge to do anything with it right now. If anyone is interested in doing their own research into the structure, I can go into more detail. For the time being, I'm done trying to add sounds directly to a BCSAR file.
That said, I think that there might be alternatives to modifying the BCSAR directly. @DeathChaos25 , I took at look at your custom DLC and I noticed that you actually include some BCSAR files in the global section. Have you been able to play sounds from those archives? If so, then custom DLC might be an easy solution for adding in new sounds, as building a new BCSAR using existing programs isn't too difficult.
That said, I think that there might be alternatives to modifying the BCSAR directly. @DeathChaos25 , I took at look at your custom DLC and I noticed that you actually include some BCSAR files in the global section. Have you been able to play sounds from those archives? If so, then custom DLC might be an easy solution for adding in new sounds, as building a new BCSAR using existing programs isn't too difficult.