They do acceptance testing of all their engines, even the current iterations. They've launched literally hundreds of these engines, with multiple tests per engine (and, as an aside, a design for Falcon 9 that is able to survive an engine failure).

They test multiple engines per week, and have the capacity for multiple times that, so losing a test cell for a few weeks need have no impact on the schedule for Block 5.

My take is that this will have essentially no impact on SpaceX's schedule.