Question about Fujifilm Ef-X500 Ttl

The flash can be rotated vertically and horizontally for indirect flash, so there's not much need for a triggered flash in my opinion.
Nevertheless, I bought a 2-metre ¨TTL Flash Cord for Canon¨ from Vello after someone recommended it on YouTube because it was better than the original Canon one. The Vello cable makes a good impression. The flash works pretty well with the XT-3 and the EF-X500 TTL, even up to 1/8000 second, but I haven't used it much yet, I must say.

With several, one master can address up to three groups, so a total of min 4 EF-X500 for such a setup, you get flash mode and power controlled. Important: Requires an optical connection. Behind objects, where there is no line of sight to the master, this does not work. This is probably why someone invented the radio remote control :-)

With some small flash on the X-T2, the remote EF-X500 can be triggered. Synch speed, 1/250 sec.

With the Cactus system, radio based, it's all a bit easier. One transceiver and one flash, for about 260 CHF and off you go. So that times two and you have a much more flexible system for the list price of an EF-X500. Even if it is not waterproof.

Only the Fuji flashes are water-resistant.

So it depends on what you want to do where.

It can be controlled as a slave. This is possible with the additional flash of the X-T2.
TTL remote control only works if the master supports TTL communication. As far as I know, the EF-8 does not.
However, two EF-X500s can exchange TTL information as master and slave.
But since I can only use manual flashes when unleashed, I don't really know the details. I use Cactus remotes and everything is a bit easier and with a little practice it is not witchcraft at all.