The titration curves were collected by measuring the pH, but the approximate equivalence points were also determined visually using various indicators that turn different colors at different pH’s. Why would you think that the color change might not line up exactly with the equivalence points?

Please see below for expalnation

Explanation: The color change might not line up exactly with the equivalence point this is because The equivalence point or stoichiometric point is the  the point in a titration where the amount of titrant  completely neutralizes the analyte solution ie equal amounts of acid and base have reacted which indicates that The moles of acid is now equal to the amount needed to neutralize the equivalent moles of base.

The equivalence point is not the same as the endpoint of a titration which refers to a color change  of an indicator but this color change occurs when the equivalence point have already been reached and so might not line up exactly to a color change.