Yep the Johnson 16 wheelers, and pretty much all the other cunning Kiwi locos were used on bush tramway (logging) lines. Some were ugly even to their mothers ??? Oddities for sure.
Price did build some main line locos so they would be termed proper loco builders, others like Johnson being perhaps more like engineering workshops making a variety of machinery for things like the logging, mining and farming industries. Sort of "you need it - we'll build it" often with ex NZR (mainline) boilers but no doubt also built from scratch.