The titles should still be there in the versions of your photos, that you are keeping in your Photos Library - the versions you shared to the Shared albums, but when you share photos to Shared albums, Photos is creating special copies for the shared albums for sharing, scaled down to 2048 pixel at the longest edge and most of the metadata will be stripped. This is done, so we do not dump large files onto the devices of unsuspecting subscribers and do not accidentally give away more information than we have intended. Shared albums are nice for showing our photos to others, but not suitable for archiving our photos, because of the reduced quality and missing metadata.
I hope you kept the originals in your Photos Library and did not delete them after sharing the photos to the shared albums, or you will be stuck with the photos in reduced quality and missing metadata.
What you could try, is ctrl-clicking one of the Photos in the shared album and use the command "Import": Perhaps you can save at least the location data by reimporting the photos from the Shared albums. The data set by the camera will usually reappear after reimporting.
That the metadata in Shared albums are stripped is stated in the footnote here (in the paragraphe "File types ...": How to use Shared Albums in Photos on your iPhone, iPad and Mac – Apple Support (UK)
"Shared Albums upload a copy of your data. Downloaded content may not contain the same information as the original."