Is it permissible to speak with one's fiancée during the engagement period with the aim of understanding her way of thinking, her principles, and her level of acceptance, and if it is not permissible, what is the alternative means for that, and can direct conversation be replaced by electronic messages after the permission of her guardian?

There is no harm in speaking directly with one's fiancée, provided that one does not seclude oneself with her, and that the conversation is for a need and within the bounds of Islamic etiquette and morals. Her ruling is like that of other non-mahram women. Islamic law has permitted looking at her for his need, and this permission is restricted by two conditions: that it be before making a decision about the engagement, and that it be in the presence of a mahram. It can be repeated once or twice. Correspondence is less restrictive than direct speech, and it should be only for a need and within the bounds of etiquette. What is needed can be ascertained from one or two conversations or correspondences. However, continuing beyond that leads to what Allah has forbidden.