I can explain specifically how the audio bumper is determined and what the issue is.
Kodi uses FFmpeg to analyze movie streams. Below are the DTS & Dolby codecs, including the codes that get returned and what that's translated to in english.
dts -> DTS
dca -> DTS
dtsma -> DTS-HD Master Audio
dtshd_ma -> DTS-HD Master Audio
dtshd_hra -> DTS-HD Master Audio
dtshr -> DTS-HD Master Audio
ac3 -> Dolby Digital
eac3 -> Dolby Digital Plus
a_truehd -> Dolby TrueHD
truehd -> Dolby TrueHD
The problem is that FFmpeg doesn't know the difference between TrueHD and Atmos or DTS-HD and DTS-X. So there's specific code that looks to see if it is Dolby TrueHD and then checks to see if the word Atmos is in the file name. If so, it reports it as Atmos. The same process is true for DTS-HD & DTS-X.
Dolby Digital Plus with Atmos has been added to our test build. If there aren't any issues, this will be included in our next version.
As of right now, I'm not sure what else we can do to get it to show correctly for those files. We've talked about reading from an .nfo file, but that still requires the person to do additional work or have a different type of setup.