Total energy of universe seems to be equal to zero too: all positive energy of universe (in which rest mass energy term mc2 dominates) by some strange reason is exactly equilibrated by the total negative gravitational potential energy (of all this matter attracting each other).

So, universe did not borrow any energy from the vacuum in "creation" process. By other words, spontaneous "precepitation" of universes from vacuum does not contradict energy conservation law (as well as other fundamental conservation laws - momentum and angular momentum), thus is not prohibited.