Historically Roland has put bass inversion on everything-- until they started making the cheap, rebranded Yamaha junk in the last year. It's true that the Prelude doesn't have a bass inversion button on the PANEL. But the board has the function and it can be controlled by a footswitch.
Yamaha does not have a provision for bass inversion until you get to their "professional" arrangers PSR-s670 and above. Even then, it's not a separate real-time control, it's bundled into the chord recognition mode. Which are weird and more difficult than Roland anyway.
Korg was also pretty good until this year. The new low-priced toys they rolled out bundle bass inversion into the chord recognition mode (which is a big step backwards in functionality and playing difficulty
) Thankfully, their MOTL (Pa700 & up) still have it as a separately controllable function.
Bottom line, a lot of the new keyboards introduced by Roland and Korg this year are toys that I wouldn't buy for a kid. But if you stick with Roland and Korg MOTL or higher, the keyboard will recognize pretty much any chord, and also allow you to optionally specify the bass, or play in any inversion.