I haven't come across any news or information that would suggest Matthew Espinosa has a particular interest in reading fanfiction. Fanfiction is often a niche interest within fandoms, and while many people enjoy it, we can't assume he does without evidence. He may be more occupied with other aspects of his work and personal life, such as collaborating with other influencers or working on his own projects.
In the comics, Rosita meets her end in a rather unexpected and tragic way. It happens during a major battle or confrontation with a powerful enemy group.
Rosita died in the comics due to a combination of circumstances. There was a chaotic fight, and she made a heroic but ultimately fatal decision to protect others.
One common theme is friendship. Often, the fanfic will show the main character becoming friends with Matthew in an unexpected way, like through a shared hobby or a chance encounter. For example, they might both be into photography and bond over it.