This is a horribly problematic election. Not only does it take hours to go through the candidates if you actually want to rank them, but you would also need to be willing to spend about a lot of time to enter them into the broken voting interface (which works great for up to 5 candidates - not for 70).
I filled about 14 candidates and it was not extremely bad, but for anyone looking to rank more candidates, I guess it might have been daunting. I agree that the dropdowns are a very inconvenient UI for this kind of votation. I can imagine something more efficient like having chips for every candidate (no dropdown), and then sequentially click on them to add them to the ballot in order, then maybe supporting drag and drop to re-order. Changing the order of candidates once the ballot is prepared is particularly cumbersome.
Best,
Mario