Excellent!
There are ways to generate in-between frames artificially. The general term is Optical Flow processing. But it is error-prone and slow. There is also depth-aware processing (DAIN) to improve on it, but still error-prone and slow and requires pretty beefy GPUs. These techniques never look as good as the real thing. The best look is when devices capture at matching frame rates from the start (unless there is intention to speed up or slow down a clip of course).
There is also a technique called 3:2 pulldown (or telecine) that converts 24fps movies to 60fps interlaced for television. I’m not sure how well it would convert your 25fps camera footage to 30fps progressive, but it might work for shorter clips.
Here’s a brief analysis of optical flow along with notes on when it works and when it doesn’t. However, Shotcut does not perform optical flow processing. This would have to be done with an external program like Premiere or Resolve or slowmoVideo, then bring that new video into Shotcut for editing.