The answer is YES! I started WWF in 2020, exactly 10 years after I started windsurfing. By the 2021 season I was so into WWF that I have only windsurfed a few times each year since then. But the interesting thing is that I got significantly better at jibing and wave riding while windsurfing even though I wasn't practicing that discipline much. The foil taught me how to better distribute my weight over my feet which directly transferred into much better planing in my jibes. The foil also taught me to become comfortable in a twisted switch stance position which directly transferred into better frontside turns in onshore windsurfing conditions.
Yesterday we had 35mph wind most of the afternoon. We wheeled our gear down to a fairly secluded beach on Lake Erie. It was a gorgeous sunny day. I rigged a 3.3m sail and blasted upwind to the usual set of waves that break on a rocky shoal when the wind blows over 30mph for an extended period. I hit a backside top turn and dropped right into frontside heading directly down the line. A quick frontside top turn and I was back out in front of the wave. Hit the jibe and do it again. I was able to get more than one frontside turn on a single wave for the first time ever. Five years ago I was just starting to ride frontside. Since then I've had an average of 5 windsurfing wave sessions per year. So that's a total of 20 sessions. The improvement has been far and beyond what 20 sessions could possibly accomplish on its own. The WWF is what has made the difference.
My wife, Lisa, has had a similar experience. She now surfs through her jibes rather than sail through her jibes, and the motion looks effortless. Using the wave to make turns. I have carefully watched other riders who have learned WWF and I have seen those new skills transfer to windsurfing. The most common improvement I see is with efficiency. WWF forces you to sail more upright. This transfers to windsurfing, and when you ride more upright on a wave board you are more efficient because you keep the full sail exposed to the wind as opposed to pulling the sail over yourself. WWF riders are using smaller sails for windsurfing with this new found efficiency.
By learning proper wave technique with WWF you will become a better windsurfer. Have fun!