For the difference between tenencia and guarda see this Proz entry
https://www.proz.com/kudoz/spanish-to-english/law-contracts/...

You could say: 'Approval of the Agreement on visits and physical and legal custody' but I'm not sure this is all needed.

5 If the parents conclude an agreement on the question of parental responsibility, which formalities must be respected to make the agreement legally binding?
Parents who reach an agreement on issues of parental responsibility must submit a signed Regulating Agreement containing all the points agreed on. This must set out expressly, in addition to other measures:

the care and custody of the minor;
the visiting arrangements with parents;
the exercise of parental responsibility;
the use of the family home;
the maintenance allowance for the minor.
The Regulating Agreement is submitted together with the application to the appropriate Court of First Instance. It must be ratified by the parents in court. After hearing the minors - if they are old enough - and the public prosecutor, the judge assesses the agreements.

Unless they are damaging for the children, agreements by the spouses adopted to govern the consequences of annulment, separation or divorce will be approved by the judge. If the parties propose arrangements for visits and communication between grandchildren and their grandparents, the judge may approve them after having a hearing with the grandparents in which they give their assent.

If agreements are rejected, this must be done through a decision accompanied by reasons. In this event, the spouses must submit a new proposal for approval by the judge, if applicable.
https://e-justice.europa.eu/content_parental_responsibility-...