Are the mentioned situations—which involved the husband embracing and kissing his wife for short periods and in the presence of family members nearby, without intercourse—considered valid seclusion (khalwa shar'iyya)?

Divorcing a wife before consummation or a valid seclusion (khalwa sahiha) is an irrevocable divorce (طلاق بائن), meaning the husband does not have the right to take her back except with a new contract. A valid seclusion is one in which sexual intercourse can customarily occur, and it requires complete privacy such that the spouses are secure from anyone else seeing them. As for mere brief privacy with touching and kissing without security from others entering, it is not considered a valid seclusion.