1) True - but was 'sovereignty ceded'? By legislative vote? Referendum? Treaty?
Not so much. It was 'ceded' when the ECJ 'took' the power. 'Ceding' wasn't a vote or referendum, it was more or less recognizing the ECJ's power grab. Justices in the national courts started 'recognizing' the ruling, and because France has a weird constitutional basis in 1958 which recognizes treaties above their own law ... ECJ becomes the supreme court.
Nobody voted for it. There was no specific legislation. There was no specific treaty. It just happened like legal dominos falling over one another after a niche court ruling.
In Germany, we are not really sure what the situation is. The Germans said that their federal court could 'review' ECJ rulings, but never did. So what is the legal standing? Well the FCC (Germany) finally did take an ECJ case to task in 2020 and now ECJ Supremacy will be tested.
It's basically crazy that in 2021 nobody really knows who the Supreme Court is in Europe and in what areas. Here is the case. [1]
By the way - the French recognition of ECJ rulings depends on reciprocity, meaning, they only respect the rulings if the other states do. If Germany decides that it's courts have jurisdiction in Germany ... then this puts France's recognition of ECJ in jeopardy. (They did a constitutional review 20 years ago and had to ensure this 'reciprocity' which will be called into question by this Germany 2020 FCC case.)
It's basically kind of absurd that there is this much ambiguity in one of the major pillars of liberal democracy.
2) Yes, as you point out, the ECJ specific areas, but notably, the 'The Charter of Fundamental Rights of the European Union' is a vague, and therefore very widely scoping document. In Canada, after the introduction of such a charter, a whole host of laws where overthrown and the Supreme Court changes their minds about things and do as they please with vague wording such as 'freedom of expression and conscience' etc.. So this brings up some complicated questions for the EU as well on this. Rulings on this charter can delve into anything.
[1] https://www.clydeco.com/en/insights/2020/05/germanys-federal...