I don't think I can answer the original question posed, but I am not sure there is a clear answer. You can tune a dulcimer however you want, but that doesn't mean that there is an official name for the tuning. The Canadian dulcimer player Rick Scott has written lots of tunes in strange tunings. He doesn't have names for them; he just tells you what notes he is tuned to.
There are basically two ways we name tunings. One is by the mode that is available on the melody string (assuming there are no half frets and the melody is played only on the melody string). In that nomenclature, we do not have a choice about the drone strings. They have to be the 1st and 5th notes of the scale, although they can be reversed. DAA is ionian and ADa would be a reverse ionian. DAC is aeolian and ADC would be reversed aeolian. What is reversed is simply the order of the drones. The tuning of the melody string has nothing to do with whether we call a tuning "reversed" or not.
The second way of naming a tuning is simply by labeling the strings according to their scale position. DAA is 155, as is GDD and so forth. DAC is 157, FAC is 135, etc.
(For what it's worth, I much prefer naming tunings according to scale position since it avoids the obfuscating modal names and is easier to transpose from one key to another. Additionally, since many of us have extra frets and fret across all the strings, we are not limited to a single mode in any given tuning, making the modal names technically incorrect and certainly misleading.)
So one way to label your tuning would be to establish the key and then determine the scale position of the strings. If @strumelia is correct, and you are playing Emma's Waltz in G aeolian (and the song is certainly in aeolian) then your Bb is the m3, the G is the 1, and the F is the 7. So we could say simply that you are tuned m3-1-7. But we cannot call that an aeolian tuning because the drones are wrong. I think perhaps the reason it sounds OK is that the minor third is one of the notes--and one of the defining notes--of the aeolian mode, so it sounds reasonable.
If you were to tune the bass string to D, so that you were in DGF, that would be a true reversed aeolian tuning.
Dusty T., Northern California
As a musician, you have to keep one foot back in the past and one foot forward into the future.
-- Dizzy Gillespie
updated by @dusty-turtle: 12/14/20 11:22:16AM