Yes, the UW could be below median, although the median weighted is lower than 4.3. The point about highest rigor is important too; as part of the counselor recommendation, the school counselor will be asked about level of rigor, and if they do not say that the student pursued the highest rigor available, that will weaken the application. Overall, I think both Tufts and Wellesley are pretty reachy for an unhooked Boston metro area student with this profile.
Some students want to shoot the moon in the ED cycle; whether this is wise depends on one’s fallback position. If UMass Amherst is affordable and OP is okay with going there, it’s an excellent school for all of her interests, and ending up there would be a good outcome by all objective measures, so risking ED1/ED2 rejection is not so bad. OTOH, if (for example) Smith or MoHo would offer a significantly better deal financially than UMass, or if OP very much wants a smaller/private school, then going the high-risk route with a high-reach ED school may not be the best strategy.