[ROSOBORONEXPORTCORP]

I think it would be great to see Ta-183 or Me-262HGII with these weapons - for example 2x 20mm and 2x 30mm

Why mix 'em? They would probably put 4 of the same - helps with aiming when all guns have the same ballistics...

The Me-262A1/U1 had a mix of 103s, 108s, and 151s. Having different ballistics can round out a volley, especially at mid-ranges (ie. a 103 provide central accuracy, 108s provide rate of fire). That said, all of the proposals (about a dozen) for mountings of 213s that I've seen had them replacing the cannons (a pair of Mg-151/15 or Mg-131s was often retained, though).

In reality the unreliability of the 213s would have likely seen them mixed with more conventional armament. In reality the 213s were also never deployed.

I view it is extremely unlikely that more than a handful of a couple of types of aircraft would have carried them even if the war had gone on another year.

If one were to create a new slot for an existing aircraft giving the Ar-234 its correct payload options or giving the Lagg-RD its correct thrust rating would both make more historical sense (as would an X-4 armed Ju-88 for that matter)