I have a Swiss keyboard where the ']' is created with the CTRL-ALT-5 key combination. I remapped it to the 'à' character as so:
keymap.set({"n", "o", "x"}, "à", "]", {remap = true}) The remap works in normal mode but not in the help files. What am I doing wrong?
Create a mapping for the actual command you want to use. That's <C-]> in this case.
Some minor remarks: using a non-recursive mapping is preferred both in general and in this instance. Mapping in operator-pending mode seems superfluous but that's the default. Either use the default or create the mapping only for normal and visual modes.
The resulting Lua code would be either of the two
keymap.set({"n", "x"}, "à", "<C-]>") keymap.set("", "à", "<C-]>") The latter would be equivalent to the following Vimscript:
:noremap à <C-]> 
remap = true? This is usually not what you'd want. And why not use<C-]>as mapping target as this seems to be the command you ultimately want to run?:help map.txtuses "remap[ping]" in this specific meaning.