Your understanding here is fundamentally wrong. Regulators in the US said very early on they were against this merger and were going to fight it. So most of what goes on in the meantime is Adobe and Figma (a) seeing if they can give something up to appease regulators (e.g. it's common for regulators to only sign off on a deal if one of the companies sells off some assets) or (b) decide if they're going to fight the regulators in court.

Your idea of the regulators just "dragging their feet" is incorrect