You’re right—hosing it down is not recommended due to electronics and potential water ingress. Here’s the best practice:

Manual Cleaning:
Use a soft brush (like a hand broom or old paintbrush) to remove wet grass and debris.
For stubborn clumps, a plastic scraper (never metal) can help dislodge material without scratching.
A damp (not wet) microfiber cloth can be used to wipe off remaining residue.
For wheels, check for tangled grass and remove by hand.

Compressed Air:
If you have access, a can of compressed air (like for keyboards) can help blow out debris from tight spots.

Drying:
After cleaning, leave the YUKA to dry in a sheltered area before charging or storing.

With regard to iNavi, I believe this is essentially RTK delivered over Wi-Fi or 4g and are not two separate entities. I have not tried switching between iNavi and the RTK station, but will give it a go and report back here. I did switch from RTK to iNavi and if I recall correctly, my maps remained (again I will try this and see what happens)

To be honest I have not tried remapping, but again will give it a go and report back here what can be adjusted and what is lost when doing so.

Thanks
Mark