Much older, but you forgot the bands he was previously in, of which he was the producer for some of those albums, as well...
Sheriff - Sheriff (1983)
- He was the primary songwriter, played keyboards and guitar. Biggest hit was the ballad "When I'm With You", which actually became a far bigger hit when it was re-released 5 years later, after the band had already broken up. (I recall there were quite a few "post hits" going on then, too). When they split up, he and bassist Wolf Hassel formed...
Frozen Ghost
- Frozen Ghost (1987)
- Nice Place To Visit (1988)
- Shake Your Spirit (1992)
- which was really Arnold's show, despite being initially a duo. Lanni wrote all the songs, sand lead vocals, and played all the guitar and keyboard parts on the first two albums. For the third, Phil X supplied guitar and some vocals. Their most well known songs were "Should I See" (off the debut) and "Round And Round" (off the second album).
Sad to admit I know all this because I am old(er), and this was how I first became aware of him. It was initially a bit of a shock to see he was the producer of Naveed when I first picked it up, but that was also part of the reason I decided to get it, too. I don't think there's much an OLP fan would necessarily dig here, but you never know.
And one other I didn't see on your list...
The Gufs - The Holiday From You (1999)
- he was producer, and co-wrote most of the songs