I'm sorry I really can't help you! I didn't have the chance to work with catalogs for a Wix website!
I have experience with the Squarespace websites in which I uploaded the catalogs manually, and it did work!
I'm sorry you are having trouble implementing the Pinterest tag on your website. I'd recommend taking a look at a few articles like adding event code and installing Pinterest tag. However, since we don't have specific instructions for Wix websites yet, I would suggest you reach out to your host support team so they can guide you or maybe to a web developer.
I understand this may not be an ideal solution, but keep us posted on how these suggestions work for you.
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The base tag can be added as custom code under Marketing &SEO/SEO Tools/Site Verification/Custom Code. Certain event codes like Page Visit can be loaded this way as well. I do not yet have a good answer for other more "click specific" events like add to cart. Also I am still working on dynamic variables for Product ID and some others.
I built my catalog in a static .csv file which I update manually. I run an ftp server on my pc (filezilla) so that pinterest can ingest my catalog once a day.