Where is the config file for Momodora Reverie Under the Moonlight

I have the slowdown issue with this game that require vsync to be disabled which is done by modifying the config file

This is supposed to be where the config file is: https://pcgamingwiki.com/wiki/Momodora:_Reverie_Under_the_Moonlight#Configuration_file.28s.29_location

Here is where the game files are on my computer

/home/me/.steam/steam/steamapps/common/Momodora RUtM/

I see no config.ini anywhere

Well, I don't know if the page you linked was updated since, but it gives the configuration path on Linux:

$XDG_CONFIG_HOME/MomodoraRUtM/config.ini

which most likely is

~/.config/MomodoraRUtM/config.ini

I just fixed my 48 FPS -> 60 FPS by disabling vsync there (although I did it on Windows), it works great!