Nope.. Up to now I'd seen nothing but 2x2 in pictures and schematics, and only 2x3 when the rockets were 15cm and this on an Me 210 picture. But this reference is to a document dated May 15 1944, and it lists+depicts the rocket kit as 2x3.
(Image removed from quote.)
"Vorhanden"
Also listed as Vorhanden is a choice of ..
2x BT 400
1x LT 950
1x SC 1800
1x BT 1800
1x Qu-Rost
Listed as "Boden" under "Ausbau" column, for 97 kg extra weight (sounds like that's the attachment eqpt for these) and "Bis 30" kph penalty which I assume stands for "more than" 30 kph.
Vorhanden= "Available"
Im Entwurf= "Under development" or "Planning"
In this case, all options were marked as of 15.5.44 (May 15, 1944).
I need to look it up, but I do believe I've seen a picture of a 410 carrying 6x WgR21's. (2x3 per wing). There may be a significant jump in the speed penalty (would be a decrease to the current penalty listed under "geschwindigkeits-verlust of 20KpH), or even the way the tubes are rigged by the groundcrews, who would have been used to lining the 2x2 system, which explains the existence of fewer examples of photos of it. Pilots may have felt it was too much penalty for a relatively hard-to-shoot/ unproven weapon, and carried the 2x4 configuration instead, or none at all. Remember, they would have had to deal with a longer exposure time in a slower/larger aircraft around escorts... so, one wonders if you'd strap the full possibilities to your airframe, especially considering the rockets were so difficult to aim historically, and you retained a speed penalty even after firing off the rockets.
Sidenote:
Geschwindigkeits-verlust= "velocity lost"
Bis= "twice" generally, so that might equate to the penalty per wing, and bis=x2.
Ausbau can mean a crapload of things depending upon usage...I think in your usage it means "conversion" though I could be wrong. Snailman would be the source on that.
Boden= "ground"