Hi,
I used to do a bit of style converting
( personal use only) back in the early 90's between my keyboards . One thing I did notice, the style never sounded as good as it did on the original instrument, even after tweaking.
Also the keyboards back then didn't have some of the features available now for creating your own styles.
Morphing ( I think Terry called it) I found is a great way to go, if your keyboard has the function. It can mix parts from different styles internal & user, to create new ones.
I tried a bit of an experiment on my kn7 with a wersi style that a friend sent me.
I put it through the style conversion program , and it sounded nigh on unuseable. If I hadn't been a case of really wanting this particular style, I would have just thrown it in the bin. Instead I decided to see if I could fix it.
The bass, piano & guitar parts, ended up sounding quite good with just a change of instruments and volume adjustments, but the drum parts were woeful. They didn't convert too well.
I ended up using the "morphing feature" ( pattern copy page 2 in my kn7) to give me new drum patterns. I auditioned some of the kn7 styles, found one with similar drum patterns to the wersi style I was editing, and replaced the drum parts using the "morphing feature".
Now it's sounding quite useable. I could probably add additional parts like strings, using this feature also.

The kn7 also has a midi to style feature. I've found that even though it's not that simple to create an actual style from a midi file song ( because of all the chord changes) I've used it for creating styles from BIAB and from my other keyboards by recording the style parts as a midi file.

There's all sorts of things you can do to create your own styles, just depends on the features of your keyboard or the software available for doing it.

best wishes
Rikki