If you mean the seal on the actuator assembly, you can buy the entire assembly as a single unit and replace the entire assembly at once. But this is assuming it is the seal on that assembly and not just a bad/worn bowl flapper seal or a crack elsewhere allowing fumes to escape where it was never intended to escape.
As for repairability, lots depends on the year it was manufactured as the newer ones have more replaceable parts instead of entire assemblies.
I have the low profile unit so the floor flush ones are actually more of a hassles. That pretty much dictated the replacement for me being a hand flush. I did look into the Aria Deluxe with the electric push button flush and was thinking of just relocating the switch panel to the wall, but alas too much $$$ and to much work for my little RV (not to mention thinking how many times I'll mistakenly flush instead of turning on the lights, or turning off the lights when I meant to flush!).
