Is it religiously permissible to marry someone who concealed their real age and educational background, and what is the correct course of action in this situation, especially given the family's distrust of him?

It was not appropriate for you to defy your family regarding their opinion about the financially unsuitable young man, then the issue of lying and concealing facts emerged, which shakes trust and respect and leads to a loss of security.

Although Islamic law permits marriage to a Muslim young man who lies if you accept that, the more important question is: Are you prepared to bear the consequences of marrying someone with whom trust has been shaken from the beginning? And can you convince your family of this, especially if this behavior (lying) is not just a fleeting slip?

If the young man is generally of good character and religious commitment, and the lie was merely a slip, then there is no objection to the marriage, provided you appease your family and convince them. However, if he is known for bad character or weak religious commitment and trustworthiness, then you should not proceed with this marriage.

It is important to discuss with your family rationally and seek guidance from Allah Almighty (Istikhara).