I'll offer you a somewhat different take on Walther backorders than those who have gone before.
Walthers, in most instances, is a wholesaler and not the manufacturer. Many of their smaller suppliers seem to produce their products only at (long) intervals. Thus, a wait may be long through no fault of Walthers. They do eventually come through but I know that I've waited up to 18 months on a few orders before the item showed up.
On the other hand, it appears to me through a recent experience that Walther may also wait to order from their suppliers until a demand has built up for some out-of-stock item, or multiple items, from a given supplier. A short while back I needed some Mirco Engineering EL kit parts and girders. Walthers had them listed as out-for-stock, with no expected date of arrival. I checked back several times over a number of weeks without any change occurring. Finally, I thought of contacting ME directly to see just when they would be producing the item. When I called, I was asked just how many of the items I needed, because they could supply me with all I could possibly want...from stock! They also informed me Walthers had not contacted them for any parts for quite some time.
So....take your pick of situations, I guess.
NYW&B