Seems like the original contributor could be presumed to have implicitly authorized, indeed welcomed, corrected versions as replacements, regardless of the magnitude of the resulting change.
A big mistake is being made if contributions from individuals are viewed as "belonging" to the those contributors, if contribution from DP are viewed as "belonging" to DP, or if contributions to PG are viewed as "belonging" to PG. On the contrary, all these things "belong" to the public, and respect to the public, and to the artistry of the original author, requires that we "get it right" and if and when we don't "get it right" then we need to work diligently and expeditiously to "get it fixed." It seems that part of the problem HAS been that contributions from individuals have started to be viewed as "belonging" to the those contributors, and contributions from DP have started to viewed as "belonging" to DP, leading to reluctance to fix problem when they are found. Part of the problem is that the donkey-work of HTML typesetting has itself become viewed as a form of "artistry" and "authorship" at PG and DP -- which it certainly IS NOT. Rather, it is simply typesetting. Which is still no excuse for doing it so badly.