Hi!
1. It happens only when the text is not available on the results page excerpts. I have enabled the search results override feature, so the same results are placed on the results page. Now it should be okay.
2. I have tried the checkboxes, but it seems to work all right on my end: https://i.imgur.com/djFpG9W.png
I’m also trying to get a result counter working in the filters so that users can see how many results there are per each post type and possibly even hide post types in the filter list with 0 results.
I’m afraid there is no such feature for that.
Is it possible to highlight synonym words as well as the search word?
Unfortunately synonyms can’t be highlighted, only the search phrase that was entered.