Dragos:
I helped another user out with a similar problem to this. One of the problems they had (and I think you might to) is they were using wix data AND wix dataset to try to managed their repeater Items in the search. This will lead to a bad result (as you are experiencing). What you probably need to do is use the search code that you have used from Ethan in a dataset.setFilter() statement. Then what you will see is that the repeater will only display the search results AND you should be able to page through the results correctly. If you don’t have a dataset attached to the repeater then you will need to manage the result set and paging by changing the repeater .data array with a page length of results that you pull from the wix data result set.
Hope this helps