Font family not correct when using 3D Camera Tracker

Select the text layer, Reset the Character Panel and the font should change to Helvetica 36 point or something similar. If the text layer does not reset then you didn't have the layer selected, the type tool was active and the cursor was between letters.

If you can't get the text layer to reset then start a new 2D text layer and see if you can get that to work. If it does, make the layer 3D, hold down the shift key and parent the new layer to the problem layer. This will snap it into position. Now delete the problem layer.

If you are still having problems try a new comp with nothing in it but a text layer. If there is a problem with that then quit AE, Reboot and relaunch. If you are still having problems with a simple text layer uninstall using the Creative Cloud app and re-install.

There is nothing in the camera tracker that has anything to do with fonts so the problem didn't come from there.

Pressing the U key twice with a layer selected will reveal all modified properties of the layer. A simple text layer will at least show Source Text and it will probably show position. You didn't press the U key twice to reveal all modified properties of the text layer because I can't see source text and I know it's not at comp center.

Doesn't look like Myriad Pro Regular either but I can't see the entire character panel and don't know what else you have done to the font. Select the text layer, reset the Character Panel using the Popup menu under the three lines at the top right corner of the Character Panel, then set the font to Arial.

If that fails, select the text layer, press the U key twice to reveal all modified properties of that layer and show us what is going on.