Are the words exchanged between the father and the suitor—as mentioned—considered an offer and acceptance, bearing in mind that it was not registered in court? And is his renunciation considered a divorce? And what are the consequences of that?

If the common understanding is that the words exchanged between the father of the girl and the father of the young man are for engagement (khitbah) and not for the marriage contract (nikah), then the marriage contract is not concluded by them. It would merely be a promise to marry.

However, if they intended for it to be a marriage contract, and the young man's father contracted the marriage for him without his explicit authorization, but the young man later consented to it, then there is a difference of opinion regarding the validity of this contract.

If the young man had authorized his father to conclude the contract, then it is considered to have been concluded with this wording, due to the presence of offer (ijab), acceptance (qabul), and witnesses. The lack of documentation is irrelevant. In this case, the young man's withdrawal from the engagement is not considered a divorce. Rather, divorce occurs through explicit wording, or allusive wording accompanied by intention, or by a judge's ruling.

It is advisable to present the matter to the Sharia court, as the Sharia judge is the one who decides such matters.