My bike has a 2x8 speed Shimano Claris 2400 front derailleur and ST-2400 shifters. The FD is damaged. Can I replace it with the newer Claris R2000 FD? Shimano's compatibility guide indicates that it can be mated only to the ST-R2000 shifters. Is that really the case in practice? If it isn't, might I as well replace it with a Sora or Tiagra double FD (of the same stye/cable-pull)? I understand how mix and match could be a problem with the rear FD because of different indexing but aren't all double FDs equal?
The road compatibility chart does indeed say that the R2000 front derailleur not compatible with 2400 shifters.
Rear derailleur actuation ratios are fairly well documented, but I've never found a good source for front derailleurs, I do know that you cannot assume that all double front derailleurs are compatible.
Your best best is just to replace with a 2400 series derailleur. Good news is that FD-2400 units are still available and and inexpensive.