I never said that. The search engines will read what’s on the page. You determine how many tags are in the tag heat map. The search engines can see that, but you don’t show the tags after 40 (41, 42 …) so that cannot be picked up by any search engine.
Regarding tags on each individual post, please start another topic, or see how it works with the search engines to see if any sites’ tags are indexed. Like here: