Here's an interesting data point: I flew PDX-SLC-ONT yesterday, heading home on Friday. My checked bags were close-ish to the 20 minute guarantee but it looked to me like they made it with 2 or 3 minutes to spare so I didn't do anything with the "Bags on Time" guarantee.

One of the line items in this lookup says "WITHIN_BAG_WINDOW false", so I submitted a claim and got my 2500 miles.

So it would appear that this also can tell you whether Delta thinks you are entitled to those guarantee miles.