Changing the language of Roboform from Dutch to English helped with the import.
However a few issues remain.
1. Roboform doesn't export the full login url, only the main url, nothing Enpass can do about this.
2. Enpass often create new login ID and password custom fields.
In this case Enpass is also in Dutch and probably doesn't recognize the name of the fields.
Gebruikersnaam = User id
Wachtwoord = Password
A lot of manual corrections are needed to get this in order and with over 500 logins this takes a lot of time.