You are misunderstanding the situation - if the value is set by a judge this is done retroactively. Messi is allowed to leave, without the fee being resolved. This is allowed, it has happened with other players in Spain - UEFA have no remit to involve themselves. He can request a transfer certificate from FIFA right now. He has the RIGHT, to unilaterally terminate his own contract if the release clause has expired, and to sign for another team.
This is exciting because the judge would take in to account his wages and probably Ronaldo’s transfer fee (when he had a 3 year contract) - so if it goes to a judge we are looking at paying less than €100m.
This significantly increases our bargaining position and weakens Barca’s - who thought they had a buy out clause.