I noticed a minor, cosmetic detail in the QWERTY maps as shown in the app.
The bottom row of QWERTY Win has this:
Ctrl Win Alt [ space ] Alt Ctrl
This is fine, and matches what is printed on my overlay.
QWERTY Mac has:
Ctrl Alt Win [ Space ] Win Alt
That is the right set of functions, but not exactly what the overlay says. It reads
control option cmd [ space ] cmd option
Since I’m being detail oriented, “Enter” could switch to “return” on the Mac layout, too.