You can convert your KN7000 sequences to midi files using the functions built-in to KN7000 (if that is what you want to do), with some provisos and with some learning (from the manual, websites, old issues of Technote magazine):
1 - If you don't use the automated features (drum patterns, accompaniments etc), the sequences will convert to midi quite well.
2 - If you do use the automated features they can also be converted to full sequences but it is more complicated (yet more learning).
3 - If you play those midi files back using the KN7000 they will work best. Trying to play them on other keyboards or on PC will work but will need some additional editing in Musecore or preferably a dedicated midi editor, because Musecore is harder to use for that sort of detailed midi file editing.
Another option for converting KN7000 sequences to midi is to plug in the KN7000 to a midi interface connected to your PC. You would play back the sequence on your KN7000 and record the midi signals on your PC (in Musecore or preferably a midi editor). This can give you excellent results that will play back accurately with minimal editing. Again there's a lot to learn to become familiar with the midi settings on the KN7000 and with the midi programmes.
Musecore is not ideal for midi editing or recording. For that, you really should use a DAW programme such as Reaper, Cakewalk (that Bruno mentioned), Logic, Protools... or something similar.
Musecore is fine for writing arrangements and outputting midi files that can be loaded in your KN7000 with ease. It's just not great for easily recording or editing midi files (in my opinion).
The easiest and most reliable way to achieve what (I think) you want is to:
A - Write your arrangements in Musecore.
B - Save as a midi file.
C - Load the file into your KN7000 to play it back (it takes just seconds to load and play midis, you should definitely try it).
D - Make any adjustments you think are needed in Musecore and re-save as a midi file.
E - Load the new midi file in KN7000 to play it back.
Repeat D and E until you're satisfied with the results. Then you can save it as a KN7000 sequence on your SD Card. You would also be able to send the midi file to people with other brands of keyboards and it will sound fairly close to what you have written on their instruments.
You can of course record as audio using your usual methods at any point.
Another example - If you have a midi interface, you can record one part at a time into Musecore from your KN7000, just the same as if you recorded into the KN7000's sequencer one part at a time. You can then play back from Muescore via the midi interface to your KN7000 (ie using the KN7000's sounds). You could even play back from Musecore and record the playback using your KN7000's sequencer.
The topic is potentially huge, so to give any more information than that will need a full tutorial to be written, and for you to answer many detailed questions about what you want to achieve. I think we are all potentially slightly misunderstanding what you would like to do. That's because there are many things you CAN do and many ways to achieve them!
I'd be willing to write such a tutorial (or a series of tutorials) later in the summer, once my websites are completed (I'm redeveloping them at the moment).