Good luck with the surgery.

Related to the problem using the mouse in general, remember that quite a lot of CC3+ can actually be done using the keyboard. This allows you to even work one handed. Some things do get quite a bit more cumbersome, but it do allow one to keep working.

The atlas is at https://atlas.monsen.cc

Generally, the amount of reserved areas compared to the number of maps is quite low, so finding one is actually difficult, but if there are any reserved areas on the current map, there will be a button below it named "Show reserved areas". That that button does is just to enable reserved ares to show up with a hotspot just as the existing areas, meaning every hotspot marked on the map leads to either an existing map, or a place someone has reserved, while a non-marked area of the map is open for the taking.

You're probably planning to fix it already, but that farmland cutoff at the top looks a bit artificial being so straight and all. A few trees covering up parts of the edge helps a lot here.

Reducing the scale of a single fill is just a matter of opening up the fill style dialog, selecting the appropriate fill, and reduce the width/height values.

Farmland fill looks a bit too large scaled IMHO for that small island. Have you tried reducing the fill scale a bit?