Could the keyboard used become a setting in the Preferences?
For instance I am using a QWERTZ keyboard (Switzerland, and also Germany by the way), and therefore the key after the sequence hjkl is not ; but é which unfortunately is not recognized.
German and Austrian keyboards don’t have French letters on them, so the key after HJKL is Ö which works perfectly fine to control note duration in Hookpad. So this seems to be an issue specifically with Swiss keyboards, rather than QWERTZ in general.
Swiss QWERTZ keyboard also has ö on the key after l, but only if the shift key is pressed at the same time… and I just checked unfortunately shift+é = ö does not work on the Swiss QWERTZ keyboard.
There are two layouts for Swiss QWERTZ keyboards - Swiss French which has é accessible in the unshifted state and Swiss German which has ö accessible in the unshifted state. So as a workaround you could switch your driver settings to Swiss German until the devs solve the issue with é not being recognized.
Alternatively you could also enable Caps Lock while entering the melody and actually use ; for whole notes. I realize that this is somewhat inconvenient, but still much better than grabbing the mouse every time you need a whole note.
Just tried, This doesn’t work either (my ; key is the same as , shifted and is at the bottom of the keyboard to the right of the m key)
This is not a very practical solution, so I better wait for the devs to solve the issue. This is why I categorized the topic under “feature request”.
Thank you for the request. Yes, keyboard short cuts on different keyboards are a not fully featured right now, but we know of the problem but didn’t get to it yet. In the end we’ll need either some setting for different keyboards or fully customizable keyboard shortcuts.
I can confirm that Ö works for whole notes as I’m using a German QUERTZ keyboard myself. In the earlier stages of development I showed Ryan my keyboard and told him I needed that shortcut and since then Ö is working. 
Lucky you. Not the case with the Swiss French QWERTZ keyboard.