We don't get a lot of insight, but we do get some. For example, when it does come up for a vote in the Council, we'll know which countries voted in favour (something you can take into account in your next national elections).
Then the Parliament will have to agree as well, and we can see which parties there voted in favour, which you can take into account in the next European elections.
The Commission is toughest to hold accountable. The Commissioner pushing it (Ylva Johansson in this case) was nominated by a country's (Sweden, in this case) government, so Swedish voters could hold the parties in that government accountable in their next national election, I suppose, but that's a very weak signal.
Then the Parliament will have to agree as well, and we can see which parties there voted in favour, which you can take into account in the next European elections.
The Commission is toughest to hold accountable. The Commissioner pushing it (Ylva Johansson in this case) was nominated by a country's (Sweden, in this case) government, so Swedish voters could hold the parties in that government accountable in their next national election, I suppose, but that's a very weak signal.