Two switch box with 12/2 and 12/3 circuits with cojoined hot wires, is this safe?
Terminology: &quot;crossed wires&quot; is simply a &quot;pigtail&quot; so that the single hot feed can be used by both switches.
This is utterly normal and safe, done normally. Normally is with a wirenut or similar insulated mechanical splice device - I had at first thought that you'd removed a wirenut for the picture - but my second thought is that they are soldered and the joint is uninsulated, which is not normal or safe, but is easily corrected. Likewise, the neutrals and grounds do not appear to have wirenuts, and this makes me think you may need to buy a large container of wireneuts and to check every electrical box you have for wiring done by whoever installed these switches.
So, the hot feed comes in on the black wire of the 12/3 cable, and the switched hots go out on the red wire of the 12/3 cable and the black wire of the 12/2 cable. Where the 12/2 cable goes we don't know, and evidently you don't either as it &quot;does nothing&quot;. That part is utterly normal and safe. When you find out where the 12/2 cable goes, you should be able to switch something with it.
The substandard splices are a concern, and the possibility that many places in your home may have similar substandard splices (you had an amateur in this box, we don't know how far they went in your house) is a concern.