@jmgx ,
This is really an Adobe Target question you are asking and you might get more responses by asking your question in the Adobe Target community.
I happen to be pretty well versed in Target, though, so I will offer my response.
trackEvent() is a method available in Target's at.js library, typically used for one-way calls to the Target servers for reporting. These calls cannot me used to deliver content from a Target activity.
entity.id is the parameter is parameter used for Target's Recommendations capability. Yes, it can be used as a source of data do drive "most visited" algorithms in Recommendations. I use it on all of the tutorial landing pages on Experience League to drive the "Most Popular Videos" module (example--note though I use Web SDK and not at.js in this implementation)
Since trackEvent cannot deliver content, most Recs users with an at.js implementation would prefer to use the getOffers() function to pass the entity.id on a product page. This way, the call is used to both increment views on the product, and can also be used as a key to deliver recommendations to the page (e.g. "people who viewed this product also viewed this other product"). To use another example, I use the entity.id on Experience League pages like this one to both recommend courses using this page and to build the "More help on this feature" recommendations module.
I would suggest you use getOffer() (this is what the target-global-mbox uses) instead of trackEvent so it is more functional.
I am not sure what you mean by "uploaded by a CSV". This view data is tied to individual users and thus populated by individual calls as people browse websites.