There are numerous synonyms that can be used in place of the phrase "become cordial". For example, the term "amiable" can be used to describe individuals who have become more friendly and easy to approach. "Genial" is another term that signifies becoming affectionate and warm. Similarly, "affable" is a word that encapsulates the idea of someone becoming more friendly and easy to talk to. Furthermore, the term "convivial" can be used to describe someone who becomes more sociable and outgoing. All in all, there are many ways to express the idea of becoming cordial in a variety of contexts.