Translation problem

Hello,

Thanks for this plugin.
In earlier versions I didn’t have any problem with translations. The maintenance page was shown in French. But since last version it is displayed in English and I tried the Weglot plugin as recommended in the settings, but it is a paid plugin and it is meant to translate the whole website.
I only want to translate “Username”, “Password” and “Login”. So Weglot seems a bit overkill.
Is there no more MO/PO file available? Or can I create my own to translate these few words?

Thank you!