There are many places I don't visit that often, but still like to have (data-)cached, not the least because there are worse LTE coverage than normal. If I had the option to set the number of days in Settings, I would probably set it to 200-500 somewhere to be honest. But I don't really have issues with storage in my phone either, probably worse for some others.

In this case it's irrelevant that C:geo doesn't use the API. It can both read and submit to the corrected field with it's web scraping.

Regarding the position on map, it could either be moved after actually opening the geocache, which would be better than today's behavior in my opinion. But you could also read all cache notes from a user on startup for example. However, there are a few users with very very many, which could cause issues.

I know myself and many other Project-GC users uses Final coordinates in the Cache note field instead of as Corrected. The reason is that Project-GC can retrieve all their Cache notes and therefore know about all those, but can't retrieve all of their corrected coordinates, since there isn't such API method. That would require fetching all geocaches with their api token, which would cause quote issues.

From a personal perspective, this is something that is troubling me quite often. But maybe it's just me, and then I need to learn to be better at updating the corrected-field. If there are no votes, then it's a 100% no, for sure. If it gets a few votes, maybe you will reconsider. :)