The readme suggests this is a Linux-first app and as HDR basically doesn’t work at all on Linux(?) I don’t think it’s very surprising that this app doesn’t handle it.
It does a great job for my purposes – describing which buttons to click over email or im.
Haven't used this app for ages, but yesterday I fine-tuned the HDR settings for my newly bought laptop under KDE/plasma, definitely on Linux. That readme might be outdated (or the tool doesn't work on KDE at all)