The author’s definitions suggest you should have “Applied” in your title, which I like, but my impression is that “applied” roles so vastly outnumber “creation of models” roles globally that it’s actually the latter that would benefit from a modifier. For now, you have to rely on context (mostly the nature of the company’s primary output) when trying to interpret something like a job posting or an acquaintance’s title.

It’s not that crazy to add a couple of domain-specific prediction heads to a BERT-family pretrained model and then do a quick fine tuning. By volume that’s less common but I would guess most people are just using things off the shelf and might not even consider themselves AI engineers. I have no frame of reference though.