Unfortunately, I don’t know if there are any Z-scalers on this forum…??
It appears the Rokuhan Z track has both flex track and ‘click track’ with embedded roadbed that’s similar to Kato Unitrack (which I assume you’re familiar with as an N-scaler). You shouldn’t need to solder any joints I wouldn’t think if you go with the click track, the point of track like that is to make construction and operation easy. By the same token, I would just use their feeder tracks and see how it goes.
A great thing about click track is you can set it up, test it, run trains, without needing to fasten it down. I would suggest doing that first, trying different track plans, and only attach the track permanently (with something like Liquid Nails) once you’re sure it’s the way you both want it.
Not a Z or T scaler yet, but expect to be in time.
You certainly want to attach feeders to Z-scale track whether you solder the joints or not. For that I’d think you’d need a resistance-soldering rig, the knowledge to use it, and appropriate low-temperature solder and no-clean flux.
These don’t apply heat by conduction, from an adjacent tip, they generate heat between two electrodes in the material itself. So you can quickly bond a joint and then promptly quench it, before the residual heat starts melting ties.
You can use one of the micro-spot welders to do higher-temperature brazing with similar ability to heatsink and do ‘rapid quench’, but that’s more exotic.
I’d be interested to hear whether the use of adhesive caulk to secure the track is as effective in the very small scales as it is in HO and N.
Since the OP is going to use the “click track” version (“with roadbed”) there should be no need to solder anything - in fact, it would be almost impossible without melting the joiners and roadbed. Rokuhan click track from what I can see is very similar to Kato Unitrack, which certainly doesn’t need soldered joints for reliable operation.