Hi, we're Google, and we limit calendar reminders to 4 weeks before an event because nobody will ever need more than #640K of RAM.
Seriously, that limit doesn't need to exist. It's there because of an arbitrary decision.
#gcal is actually buggy and not great, let alone the personal-data vampire squid issue. But I'm not aware of any EXTREMELY RELIABLE alternatives for Android. Ffffffffff #googledivorce