Oops... looks like the spiders padded through here
Add products to your cart and remove them from here Lets buyNothing was lost. The plugin now keeps its text in translations/translations.en.yml, and on the first start after updating it moves your messages there for you.
What happens is:
The editor text is deliberately left out of that copy, so the in-game editor picks up the newer wording rather than an old copy of it.
old_messages.yml is only kept as a safety net. Once you are happy with your messages you can delete it, and the plugin will not read it again either way.
Everything the file can do — the %prefix% placeholder, how a translation falls back to English, and running the plugin in another language — is on Languages & Translations.
Oops... looks like the spiders padded through here
Add products to your cart and remove them from here Lets buy