How hard could it be to just add all the known distances? Probally have them stored in a database table all they would need to do is just insert the full range of distance types. This would only take a few minutes and if they dont have it in the database and its embeded in the page still would be easy to add its not like a lot of extra development would be required. Oh well they probally rarely check these forums anyway only see garmin support rebs every now and then and its usually in the hardware forums.
This would appear to be a trivial thing to add in and incredibly useful. I'm not sure that Garmin reads the forum that much though, I've hardly seen replies from staff to feature requests. It's be nice to get a "point noted - maybe we'll add it" at the very least