Accidently reduced salt in pickling recipe – are these pickles still safe

It's a vegetable. When you cooked it you damaged the cell walls and the juice is leaking out.

I think this picture only seems unusual because of the beets' color. If these were carrots there wouldn't be a question because, of course, the juice would be less startling.

If these beets haven't started to mold or ferment- and you'd know it from the smell- then they are fine.

The right way to know if your recipe is safe is to use a recipe from a trusted source. What you're doing is pickling, so just search for pickled pepper recipes. For example, I quickly found this one:

http://nchfp.uga.edu/how/can_06/pickled_hot_peppers.html

The NCHFP is one of the big authorities on canning in the US, so you can certainly trust that. You can add spices, and if desired add more salt or vinegar, but you don't want to use less - it might become unsafe.

And follow their process - there are reasons for everything. For example, all the boiling and details about how to fill the jars help guarantee that you get a good seal, so your jars will stay safe long-term. What you're doing is really prone to bad safety issues. For example, things could get colonized by bacteria while you let them cool, then you'd seal it in the jar and let it go to town. Or your seals could fail. You may get lucky for a long time, but not everyone will every time.

You should be able to find plenty of similar things from other universities, if you need, or you can buy an authoritative cookbook/reference.