The plugin ships in six languages, and you can add your own or change any of the text your customers see.
There are two separate things here, and it is worth keeping them apart.
The plugin’s own language
The plugin is available in English, Dutch, German, French, Spanish and Italian.
There is nothing to set. The plugin follows your WordPress language automatically. If your site is in French, the plugin is in French. If your language is not one of the six, it falls back to English.
Your customer’s checkout at Mollie also opens in their language, worked out from your site’s language.
Changing what your customers see
Go to Mollie Payments, then the Translations tab.
This is where you customise every text your visitors see during payment.
Leave a field empty and the default text is used. So you only need to touch the ones you want to change.
There is a Reset to defaults button if you go too far.
Why you would use this
Not to translate, but to sound like yourself.
The defaults are correct and neutral. But “Complete your payment” is not the same as “Nearly there”, and your business has a voice. This is where you give the checkout that voice.
Translating the plugin into a new language
Go to Mollie Payments, then the Language tab.
Download the .POT file. This is the standard template containing every translatable string in the plugin.
Open it in Poedit (a free desktop application for Windows, Mac and Linux) or use the Loco Translate WordPress plugin, which lets you translate inside your WordPress admin with nothing to install on your computer.
Translate the strings, and save.
Put the .po and .mo files in /wp-content/languages/plugins/. WordPress loads them automatically when the site language matches.
The .po file is the editable source. The .mo file is what WordPress actually reads. Poedit and Loco both create the second from the first.
Improving an existing translation
You do not have to start from scratch.
On the Language tab you can download the translation for any language we ship, as a starting point or to correct something.
Put your edited files in /wp-content/languages/plugins/ rather than overwriting ours, so your changes survive the next plugin update. Keep a copy of the original, just in case.
Send it to us
If you translate the plugin into a language we do not ship, or you improve one we do, email it to support@documentation.quantumaddons.com.
We may include it in the next release, with credit.
This is not a formality. A good translation from someone who actually speaks the language is worth more than anything we could produce ourselves, and we would rather every user of the plugin benefits from your work than have it live on one website.