Unless theyâve changed it in v2, you canât directly export Scala files into a Hydrasynth. You have to convert the .scl file into a .mts, which I then dumped into the HS out of Reaper. There used to be a microtonal web page that would do the conversion but it died last year and now it seems like you have to use a Python app, which is something about which I know nothing.
But unless you need to have a specific JI or similar tuning, you can use the Osc keyboard tracking to get you in the ballpark, so just as is at 50% youâre getting 24-ET quartertones and at 200% 6-ET.