[morzh]

Germans, in fact, have no problems getting things off the ground.
Either V2 or the moon rocket (same guy). Both are highly successful (depending on the point of view).

Anywho.

Joseph,

You do not need to ask about the connector rating: it is pretty much comes down to your FR-4 surface space between the solder pads of where this connector is soldered, which is the weakest point and the voltage rating of your board is no longer dictated by the connector (whatever it is), but by the surface type and its contamination. This is why the creepage for 450VDC is desired to be at least 5mm. Or, if you want 250V, then 2.5mm. Which your pads' size eats into.

That is not to say, it will necessarily experience electrical breakdown. But it is not protected from it.
Now, what you could possibly do is use some potting. Clean it well with IPA, and then apply some corona dope or any suitable electrically used epoxy to both sides. This will increase the effective creepage.
Your pins are still close to each other in the air but not as close anymore, plus the air breakdown is way better than the FR-4 surface.