Hi Baz,
Unfortunately, I am not aware of any such tools for Mac. In principle, you can also use any MIDI sequencer or DAW (e.g. Cubase) to edit Yamaha style files. In this case, however, an additional Windows program is necessary (e.g. "Style Split and Splice"), because sequencer programs otherwise destroy the style file structure.
The easiest thing would be to get an additional PC / laptop (with Windows 10). Many programs still run under Win 7 or 8.1, but there is no longer any support for these earlier Windows versions.
There are also several ways to use Windows on the Mac, e.g. with Boot Camp, Parallels Desktop or VirtualBox. However, you need a valid license to install Windows.
Best regards,
Chris
YEP ! Agree with that 100%.
Just at the moment there are LOADS of Windows 10 pc's on the market, both new and second hand. Just a quick skip through Gumtree in this area alone shows me around 17 fully working ones for under £100 and 4 of them less than £70.
The reason is that with the announcement of the new Windows 11 operating system came the fairly ridiculous news that unless your pc has TPM 2 and a processor made within the last couple of years (don't even bother yourself with all the technical reasons) a heck of a lot of Windows 10 pc's will not be able to upgraded.
So a lot of companies and individuals are getting shot of perfectly working Windows 10 computers and laptops because they want to have Windows 11. Personally I will be sticking with W10 anyway. They make perfect computers for working with Yamaha keyboards.
Apple unfortunately are just not on the same page with Yamaha....Their loss.
So there has never been a better time to grab yourself a great cheap Windows 10 pc, which will be of great use to you for at least another 4/5 years. Go get, is my advice. Get something with NO LESS than 8GB of Ram, and an SSD drive. Avoid Windows 10S edition, and go for an Intel 5 or 7 processor....you won't go wrong.
I build and repair pc's....If you want any advice just shout.