Around a year ago, I began working on a modified version of debuffed that will account for most/all scenarios on rdm, but it requires alot of user pre-input (JP,Gear,Merrits,etc) and ultimately had it working very decently, before Empy+3. It still works fairly accurately but I think I had a calculation error somewhere where certain durations were off a bit for empy+3.
However all this provides is the maximum possible durations, and there is nothing we can do for resists, except hope that debuffed sees the packet for the debuff dropping. Its very easy to not get that info from the server. But as others said, there really isnt much concrete info sent from the server to begin with, its just calculations client side of max duration.
If there's any interest I would probably post it as-is, but its in my plans to go back and retool the equations eventually. In its current state, it provide accurate (within 10secs) timers for the rdm debuffs and has built in audio cues for debuffes dropping, if the addon sees it. (This was quite useful when I was farming Odin HTBF)
Edit: One interesting issue I ran into was that there is no way from the server I could find that would tell you if a mob was an NM or not, so I had to make a decision to always assume the mob is a NM when applying durations under sabo. TLDR: its a big pita.