What's the one light question your sun app can't answer?

Hi, I'm Jaka. Sunreach goes live here today at 09:01 CET (midnight PT). It started in the Soča gorge in Slovenia: on 18 October sunrise in Bovec is 07:27, but direct sun only reaches the river at 10:27 and leaves at 14:59. Every app I tried said 07:27, so I built one that reads the real skyline.

If you plan around light (photos, hikes, a sunny terrace, the aurora), what do you still have to guess? And which spot should I test next? Next on my list: stars and the ISS over the same real skyline.