One of the issues, though, is that with the X-T2 (and the X-Pro2 FW 2.0) Fujifilm introduced new flash protocols (read also Fujifilm & Flash, The State of The Art here). This means that flashes like the Nissin i60 need firmware udpates in order to work properly.
Well, apparently Nissin is working on it. If I got the google translated version right, Nissin just said in an official press release to the Nissin i60 launch in Japan here (via dc.watch), that they are working on a firmware udpate, in order to unlock the HSS feature.
“[google translated] Regarding the for Fujifilm, with FP flash (high-speed synchro) non-compliant at the moment, is scheduled to correspond by firmware updates at a later date.
In addition, NAS commander “Air 1” Fuji Photo Film for Four for the Thirds, is expected to release November.“
Regarding the Nissin i40, FR-reader Fujica explains that “you will need to send your flash to the distributor for the update as the i40 does not have a USB port.”
As shared here on FujiRumors back in September here, Cactus is also working on a new firmware and you just have to drop them an email to get access to the Beta Firmware. ZedProMedia did it, and shared his feedback on his youtube channel here.