For search purposes I share a solution I recently shared to a similar (same?) issue;
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I think the solution is to add the KEYMAP file as a different format by saving a copy with the “.toml” extention.
Also add 2 lines:
[[protocols]]
[protocols.scancodes]
Source (end of article): 03. Meson IR: Creating a KEYMAP file from scratch · CoreELEC/remotes Wiki · GitHub