Hi Joe,
After many tests, all the problems seem to be solved just by copying the .po and .mo files to the wp-content/languages/plugins/ folder. Maybe all this mess is part of a misconfiguration of Loco Translate. I can only tell you that now I can use the plugin fully translated and that last night I suggested dozens of terms so that it can be enjoyed in Spanish. Greetings and thanks, especially for building such a fantastic gadget.