Hi, re External Flashmeter & High Shutter Speed use . . I think not.
Bobbyz posted somewhere to that effect and in my testing my L358 did not reflect what the camera's sensor captured. IMO essentially the meter has no way of knowing that 1) there is now a delay between the flash starting and the initiation of FP shutter opening and 2) the shutter opening is now a moving slot. If a meter has high shutter speeds associated with flash, I think their engineers had leaf shutters in mind.
So with an FP shutter body and above max sync speed shutter setting, I think the 'Terry toweling / blinkies' approach is probably the best to go for.
To make things even more confusing, I have a Jinbei HD-600, one model prior to the Jinbei HD-600 II which is HSS capable, and which is basically the same as the Rovelight. My model does not have any HSS settings on it, and is again not advertized as HSS.
However......... when I use my Yongnuo 622C-TX, in HSS mode, my camera syncs up just fine unless I am at full power.......then I have problems. If I take it one click down from full power, I sync up to 1/8000 no problem.
As I continue to study and learn about strobe photography I find many gifted people either shoot stopped down a lot; a few use ND filters. Most folks appear to get by without HSS with mainstream high quality strobes and don't appear to miss HSS.
What I see comes up a lot is how many photographers use a light meter to set up shots. Do many of us Rovelight users use one? Obvious followup question.......... since my camera seems to sync OK with a non HSS strobe just because my trigger is in HSS mode, would you imagine a light meter would not work accurately in that situation?