Yes, you need a derailleur that is proper for your particular gear, which will handle your relatively huge large ring and cover the range of your rings. You might want to start another post in Bicycle Mechanics and include the sizes of each of your chainrings. My first 'bent was a 2000 Tailwind and I think it had a Sora. My more recent RANS bikes - which came with with 30-39-52 cranksets - have come with Microshift FD's - RANS sometimes slaps a RANS sticker on them and calls them RANS FD's. You might consider contacting the new RANS company for advice RANS Bikes | Contact

Agree with Blazing's advice to post on bentrider.