This is a North American site for traditional three speed bikes but they don't have good news for rims. The Society of Three Speeds Tire and Rim Update.

The only other thing that I can add is that this wheel size was popular in Japan and other parts of Asia. It may be possible to get them somewhere. I was going to suggest SJS Cycles in the UK, but you are checked with them already. The 32 hole seems to be the problem.

Perhaps we need to wait another 20 years and someone in the bike industry will rediscover this tire/rim size.

I have two Sturmey-Archer Dynohubs that will likely never be laced up again. That is a shame.

I hate to say it but you might have to go with more modern dynamo hub with 36 spokes and get the rims from SJS Cycles. That is a shame, too.