Hi Niklas,
Thanks for reaching out to us and sorry to hear about this issue you are experiencing.
I’m not familiar on how Loco works, but when you update the plugin the language files -packed from our translations site before release- are included in the package and will override the old ones. If Loco stores the modified strings in the database -like Say What? plugin does- I think there should be no problems with recovering that. If it modifies the files directly in the plugin folder, I guess the changes are overwritten in the update.
Please let me know how this works and maybe we can get those strings back,
Best,
Nico