Is it permissible to continue the engagement and marry a religiously committed girl who prays and has good morals, but does not adhere to the full شرعي (Sharia-compliant) dress (she wears jeans with loose clothes above the knee), knowing that she is aware her clothes are not شرعي and has tried to commit to شرعي dress in previous periods then returned to what she was doing?

The aforementioned girl is a stranger to you as long as you have not عقد عليها (entered into a marriage contract with her). It is forbidden for her to go out in the clothes mentioned. Explain to her the ruling on the obligatory covering (ستر). If she responds positively, do not leave her, while adhering to the Islamic guidelines for interacting with her. If she does not respond, then leave her and seek out other righteous women, for whoever does not adhere to the limits of Allah will not fulfill the rights of others.