The research team had budgeted six months to complete the field study. ______, unexpected equipment failures and weather delays stretched…

The second sentence reports the eventual, actual outcome of the project after the obstacles described, and in the end signals exactly that kind of concluding, final-outcome framing. Similarly would suggest agreement between the planned and actual timelines, but a doubling in duration is a significant divergence, not a match. Namely introduces a specific example of something just named, which doesn't fit this shift from plan to outcome. Granted signals a concession before pivoting to a counterpoint, a different rhetorical move than reporting a final result.