Thanks
@Nod ...I think.
Yes I use flash after a fashion. I don't shoot people at all. My flash use tends to be more tied in with creative type attempts, many of which are unsuccessful.
I seldom use TTL and nearly always use manual off camera flash guns.
You have an X-T2 which brings in further complications. There is a new Fuji gun for the T2 but I've heard that it's not available yet. Rumour has it that it will cost £500 or so, so there may not be a big take up. As
@stupar mentions above it is unclear if existing Fuji guns will work on the T2 in TTL mode. Certainly the Nissin i40 doesn't. It's a good gun and works fine on the T1 but not the newer model. You can send it back to Nissin who will remap it for you but that cost £20 plus postage both ways. I've heard that the Nissin i60 (which obviously is a more powerful gun) works in TTL mode on the T2, but - and this is important - only the latest manufacturing batch will do. How you know one batch from another is unclear to me.
I use my old Canon flash guns - the 580EXII. I can use them on camera but in manual mode only. I fire them two different ways, depending on what I'm shooting.
1) I fit a Yongnuo RF 603 MkII trigger on the hotshoe. The MkII is very important. Don't use the MKI because they don't work! Wire it into the camera. The flash gun I have with a second 603 under it. When I press the trigger button on the 603, the flash goes off and the shutter activates. I tend to do this when using just one gun that I may want to move around for shadow control purposes. Works well. Took this on Monday using that method...

FUJI1838 by
mickledore on Talk Photography
2) There are times when I want more than one flash or want different manual settings on them. Then I get out the YN 622 gear. I have a YN 622TX on the hotshoe. Not wired in and I fire the trigger by other means (Even sometime using the 603 sat on top purely as a remote). I have a YN 622 unit under each of my guns. I can control all aspects of each guns performance from the TX on top of the camera - saves a lot of running around. This was shot using three guns controlled by the 622 gear and with the 603 sat on top of the TX purely as a remote trigger...
FXT10838 by
Frank Yates2010, on Flickr
There are YN guns that are self contained and obviate the need for separate units under the guns, but I'm not knowledgeable enough on them to express an opinion. I think the above mentioned Stupar may be able to help.
Flash is a complicated business, and I only know a very, very small bit about it. I know enough for my purpose so can't be classed as any sort of expert, but am happy to help - if I can.