pull up bar from concrete ceiling
Even though those existing anchors may be able to hold you up as you hang from the bar do you really want to trust it? I know I would not trust it. Hanging anything from a concrete ceiling is risky.

Hey even look at the fastener that you put in the picture. There is a fracture in the concrete that passes right through that area.

I would strongly suggest that you devise some type of stand for the pullup bar that sits on the floor and is built with materials that you know and trust to be reliable. Something like building an A-Frame assembly on two sides to hold up the bar.