Looks good, Mike - even better with the coupling rod in place - is there enough flex in the rods that you could get away with simply enlongating the hole where they attach to the middle driver, or would that not give you enough movement?
I'll have to take a look at one of my 2-10-2s to check just how LGB have done it!
For another cut-price Harz loco that is, in my opinion, more than "good enough" even though it's not an exact model, here's the thread on the scratchbuilt 5906 Mallet that I acquired on evilBay (and then repaired after some serious damage in transit) - worked out at less than a tenth of the price of a KISS one....
https://www.gscalecentral.net/threads/scratchbuilt-5906-harz-mallet.307674/
Jon.