Sure

It would honor me if my codes were used. Nothing too much here, though, AC speed change is not implemented for wave, mod and midi.
Here is my own version of AGS 3.2.1.111. It would be splendid if you upload the compiled engine, so I can distribute the game with it

To be honest I'm not good in Linux compiling, I consider myself lucky when I manage to run softwares in Linux, let alone compiling.
About what I changed in AGS;
AudioChannel has a
SetSpeed(int) function now, 1000 is the normal speed here.
acsound.h, acsound.cpp, acaudio.cpp files are changed. You can simply search for "SetSpeed" and "set_speed" in the files to see what I've added.
Looking at the modification dates, you'll notice that some other files have been changed, too. Like Utilities.cs. The reason is, once I had added 1280*720 as a resolution, but then removed it back. It's irrelevant to the SetSpeed stuff.
ac.cpp seems modified, as well. I couldn't figure out what I changed here, it was probably about the resolution. I couldn't find any audio speed related stuff there.