There used to be extraKeymaps folder in %APPDATA%/OpenMPT. They seem to be missing in the latest release. Is this intentional?
The actual folder folder has always been in the installation folder, not the settings folder. There merely used to be a link going to that folder in the settings folder, but only when using the installer, in portable mode this was missing. Instead, as a solution that works with both the installer and portable mode, you now find the "ExtraKeymaps" link in the left column of the open/save dialog when browsing for a keymap, see attached screenshot.
Oh, I see! Thank you so much!!