How to debug load_textdomain?

Would have loved to know that beforehand. Here is the solution to my problem, so others that are stuck might not be stuck on this for hours.

WPML has a String Translation plugin. If it is activated, it seems that it passes before the load_textdomain in priority. And so, load_textdomain works in loading the file (giving the true) but String Translation throws all of it in the trash when it loads itself.

tech