I too am disappointed (but not surprised) that STV had almost no effect at all on the outcome of this election
This may be true, but if it's true, it was only true very narrowly. The margin between the 4th and 5th placed candidates was 12.27 votes in a situation where 1,188 were needed to win.
Now that the full ballot data is available, it appears very likely that using STV did indeed change the result of the election. Though not at people had hoped.
Ad Huikeshoven has tabulated the numbers of preferences received by each candidate here:
Trying to work out what would have happened under a different voting system is obviously a bit tricky. But there are several ways to look at who would have received most Support votes. We could interpret any vote in positions 1-4 as a 'support' as in 'this person is in my top 4 picks to fill the 4 spots on the board', though probably many people would Support more than 4 candidates. Or we could interpret any positive vote as a 'support', though in some cases low preference votes are an indication of opposition.
The order of candidates in each of these cases is as follows:
Looking at top 4: Rosie, Victoria, Eliane, Dariusz (Lorenzo 5th)
Looking at total preferences: Rosie, Victoria, Eliane, Lorenzo (Dariusz 5th)
(vs the actual result: Rosie, Victoria, Dariusz, Lorenzo with Eliane 5th)
We'd also obviously need to look at Oppose votes (which of course under the old system counted 4x as much as support votes). But usually in elections under the support/oppose system we observed candidates getting the most Support also having the least Oppose (except for 2015 when the re-standing board members got many extra Oppose votes and therefore didn't get re-elected). We could also look at patterns of very low preferences, but it is really difficult to find any pattern that changes the order of the top 3 candidates there.
So I think it is a reasonable hypothesis that had the election been conducted under the old system, Eliane would have been elected and one of Dariusz and Lorenzo not elected.
It does pain me to say this, as I have often been heard arguing that STV would help make the board diverse, but it's the only conclusion I can draw based on the votes cast.
In terms of what should happen next - in my view the Board should say "ok, we're fine for people from North America, Western Europe and Eastern Europe as they're all fairly well represented" and say that 2 (or more) seats in the next election should be reserved for people who don't match that description. (Though still the next election should be under STV).