I’m making these builds, I’m French and I use my own dog food on linux (not KDE, though). Never had this issue. I just checked with the latest AppImage and less recent ones, and when I enter “lâche” with debug-keyboard on, I get:
TeXmacs] debug-keyboard, Pressed l at 18853
TeXmacs] debug-keyboard, Codes 108
TeXmacs] debug-keyboard, l -> l -> l
TeXmacs] debug-keyboard, Pressed pre-edit:1:^ at 19654
TeXmacs] debug-keyboard, Codes 112 114 101 45 101 100 105 116 58 49 58 94
TeXmacs] debug-keyboard, Pressed � at 21157
TeXmacs] debug-keyboard, Codes 226
TeXmacs] debug-keyboard, � -> � -> �
TeXmacs] debug-keyboard, Pressed pre-edit: at 21157
TeXmacs] debug-keyboard, Codes 112 114 101 45 101 100 105 116 58
TeXmacs] debug-keyboard, Pressed c at 21521
TeXmacs] debug-keyboard, Codes 99
TeXmacs] debug-keyboard, c -> c -> c
and 226 is the unicode for the expected â (and it comes with no spurious space in front). I’m curious about the origin of the “Pressed speech” in your debug output.
Has this problem ever been present on your side, or did it start recently?