On my Mac, I make use of AppleScript to achieve this integration.
For example, to set the reminder date, I use a script.
In addition to setting the date, it also adds an entry to the Calendar.
The code isn't complicated
tell application "Calendar" to tell calendar "Home" make new event at ..... end tell end tell
Applescript allows almost unlimited customization and integration. It can be used with the Calendar, Mail, Reminders, Excel, ...