I went back 18 months in posts, and searched on terms as well, and didn't see this, though I assume it is something that has been brought up from time to time. I have tried googling this as well with no success, though often a single keyword can make all the difference.
An addon to track the rez timer cycle in WSG specifically (no gy-caps to account for) would be useful. I can see great utility, esp. for a rogue, in making sure it is likely a healer-kill or other key player kill will have a 25-something second rez wait rather than a 1-5 second wait (sap would be great for this scenario when possible). That said, the fact there isn't such an addon makes me wonder if it exists or is even possible. I am playing low brackets, where subt. rogues can still 2-3 shot many classes, so often I have discretion on kill timing by some seconds.
Does anyone know why such an addon hasn't been possible to date? If the rez timers are constant (are they?), I cannot see why just using the info from either bg start or player's first death to set the mark.
I'm not sure about the desync issue in WSG since I have not tested this before, but only tested the WG and AB ones. It appears that GY changing and ressing doesn't occur exactly X seconds from the point of capture, the game only checks every Y seconds to see if it should change hands, and thus there's always a Y seconds variable of uncertainty that can slip by.