I think an useful feauture could be “Spotter maximum distance”, especially for VHF ES propagation, where the path is very localized. The distance could be calculated from the main square. I think the only possible source would be pskreporter.
For now, my workaround is to include a lot of particular calls on the radius of interest (for example 100km from me) but this list needs to be revised quite often, new calls becomes active. However, the trigger worked wonderfully for most of ES and DX tropo openings.
TNX, 73 Ady YO2NAA