I've got somewhat the same type of texture, except in smaller star shapes.
They used a brush like this packed with thick mud.
Smoosh in turn and pull away for a star.
With a dragging action you might be able to blend into the existing random pattern. Or use a clumped rag?
The rollers seem to give only a consistent pattern.
I'm liking Easy Sand 45(min dry) for blending.
It is dry but you can control the mix after stirring in a 14" tray (with 2" knife) and waiting a few for absorption.
Knock off the surrounding and do a layer at a time w/dry time until flush. Should be almost no sanding.