Is that why its death scream could be heard alongside all the Titanian humans?

No, but it was cussing, and that made it's 'voice' stand out among all the terribly polite Titanian death-screams.

Saturn Girl has been able to communicate with animals (at least, in the Adventure era stories, when anything was possible). Perhaps Titanians can establish some mental connection to any living being. This wouldn't make the mayfly telepathic, but could explain why its death cry was heard.