Salut Émile,

When sending keyboard shortcuts to a program, it can easily happen that your script is too fast for the concerned program which isn't able to digest all the commands it receives quickly enough. Adding a small break ("Sleep" command) between the individual shortcuts you send helps with that and provides enough time for Studio to handle each command.

#IfWinActive, ahk_exe SDLTradosStudio.exe
^r::
SendInput ^{Ins}
Sleep, 150
SendInput !h
Sleep, 150
SendInput, u
Sleep, 150
SendInput, r
Sleep, 150
SendInput, ^l
Return

You might have to adjust the sleep duration (e.g. from 150 to 200 or 300 milliseconds) if it doesn't work out of the box.

I have also added the "#IfWinActive" command, which makes all hotkeys beneath it context sensitive, i.e. they only work when the Studio window is active.
If anything is unclear or still doesn't work as expected, please let me know.

Cordialement de Bruxelles,
Raphaël