Without documentation, it's hard to say. It does appear that the SoundExe values are all comprised of the left most X characters of the name, although I cannot see a pattern as to how many values are used for each name. I don't think there is an algorithm that will reproduce the values.

Since you cannot find code that inserts the data and it appears to be static, I would suggest finding all of the code that queries the tables and go through it until you have a very good understanding of how the data is used. Then use your knowledge of the data access rules to manually change the CompanyName and SoundExe values. This is the only way I can think of to ensure that once you change the values, your queries will still return the expected results.

This is probably not the majic answer that you were looking for, but unless someone else chimes in here, I'm out of ideas. You should also find the guys who originally designed the system and pummel them upon the neck and head :D.