When I was looking at them seperately I couldn't shake the feeling that the Holst unit on regular Hrududu and Thethuthinnang Hrair have different details, but I compared them side by side and they are the same after all, with the only inconsistencies coming from the resolution difference. Curiously, when overlaying them they don't match the proportions exactly, but I'm chalking that up to the difference in the central structure - switching Hrududu for Hrair parts makes the whole thing a bit wider.
One thing I'm still wondering about is how do the cylindrical drum frames attach there. Based on the latest volume I'm fairly confident the boosters are connected directly onto the same latches as the wing units, but the Marasai art makes it look like it might be between them afer all. Hrududu's solo lineart leaves little room for doubt they're separate, and it looks like they mount onto the wing unit latch together with the boosters which is a bit strange to me. On Thethuthinnang Hrair it's harder to tell due to the claw units - which is the other weird thing.
On independent Thethuthinnang Hrair, the claws have their "top" sides to the left and right, whereas on the Marasai they seem to rotate and these are facing upwards. Similarly on solo Thethuthinnang Hrair the boosters look like they're beneath the drum frames, but on the Marasai it's like they're on the same level.