Opensolr Accounting is in Romanian, whatever language the browser asks for. English is a full translation of every screen, chosen by each person for themselves.
The sign-in, sign-up and setup pages have Română · English at the top. A click switches the page, and the browser remembers the choice.
Contul meu › Profil și limbă (My account › Profile and language), field Limba interfeței (Language of the interface), then Salvează (Save). The language is kept on the account, so it follows you on every browser and device.
Invitations and the mail with a new account's one-time password are always sent in Romanian.