Yes, when you change the code of the plugin, this will get overwritten with the next update. The recommended way to overwrite output for the EXIF display is the filter lbwps_caption_exif, similar to the other filters as described in the FAQ (I just forgot to mention, that there is also lbwps_caption_exif). So you could use str_replace() to replace f/ by 𝑓/ in the output.
However, I can apply your change to the next update as well.
About other EXIF fields: unfortunately EXIF is not a simple key-value-list as one might expect (also see here: https://exiftool.org/TagNames/EXIF.html). Some manufacturers do include the lens name, others don’t and some use EXIF ID 0xfdea (Lens) for this others require to use EXIF ID 0xa433 (LensMake) and 0xa434 (LensModel).
In fact I don’t have any example image in my collection where the lens name is included. So if you have some sample images for me to test, this would be very helpful. Then I add this as additional backend option along with a styled output for the caption.
In addition: even my camera adds the lens name to the RAW file, after converting it to JPEG the information is lost, only aperture etc. will stay. So I have no chance to even test this yet, sorry!
Ok, I managed to identify the information – unfortunately the PHP EXIF extension does not support it, so I did take some research how to extract that. I will provide an update which includes the nicer f-stop indicator and optional lens name as well.
Version 5.3.1 adds lens names as additional option and the modified f-stop symbol.