Language files deleted after each update.

Hello
After each update of Restropress plugin, my two language files:

restropress-fr_FR.mo
restropress-fr_FR.po

are deleted, And i found in language folder two useless language files:

restropress-nl_NL.mo
restropress-nl_NL.po
I delete that fu***k nl-NL files to replace by my own fr-FR.

Do you put that nl_NL language files everywhere? (and why nl-NL?)

That not very important, but highly irritating.

Thx!