Checking further, today:
B-209L did do a test flight on 16/4 and a commercial return leg on 17/4.
B-209M did do a test flight on 17/4 and a commercial return leg on 18/4.
All the rest still grounded, with 4-5 B737-800 scheduled to fly on 19/4.
So, "slowly" "ungrounding".