First I want to address Guillaume's topic:
Dear Good Sir,
In this instance (because every situation is different), I would correct both actions. Just as you pointed out already - you correct "Both or none." In this case you definitely correct both. It does not matter if the amounts are large or small. The fact is both players raised, which means when it gets back around to them, they will still have all their options open (Call, Raise, Fold).
Where substantial action falls into play here is only if the bets were not corrected prior to the flop or there were multiple under-calls prior to or after the flop. Using your example:
A checks
B bets 900
C raises 2100
D raises 3600
E Calls 3600
A Folds
B raises 4900
C Folds
D CALLS
E CALLS.
Many times I've watched a TD try to correct this by backing up the action. This is a mistake. In this example the action is complete. Do not correct the bets. Move on to the next betting round. If the action is incomplete, correct the bets.
Accepted Action is more of a term used for incorrectly stated amounts, specifically for All-in situations, but sometimes on regular betting rounds as well. Mainly this rule covers situations where player A bets and player B asks player A or the Dealer how much it is and the amount stated is incorrect compared to the amount counted down to pay off the bet at the end of the hand (All-in) or at the completion of the action for that betting round.
We do not need a TDA rule for this. I am firmly in the court of Dave Lamb, when he says the TDA is going down the wrong path by making all these "rules". Going off topic, when I compare the original guidelines created by the TDA and compare them to now I think two things: Two steps forward, one step back.
P.S. - I like Mike's reference to "correcting within the betting round" But only if the action is incomplete.