Thank you for the log-in details, I was able to find the causes of the problem:
1. Main problem: Because you have priorities set and the results limit is 10, the plugin will always display the results in the priority order, and cut out the rest of the matching results: https://i.imgur.com/9dIPOZ6.png
In your case 'muschio di quercia' matched a lot of results, but only the top 10 with the highest priorities was displayed.
I highly recommend changing back all the priorities to the default value 100, otherwise this will affect the search results too much: https://i.imgur.com/l62x2nY.png
2. I believe that this logic configuration might be better for your case: https://i.imgur.com/J2OyWJr.png
Because if the Exact matches are enabled, then the index table is not used at all. I have made this change, but of course you can change it back if you want it to.
3. The ordering options are probably set incorrectly, both values were 'by date descending': https://i.imgur.com/A3ZiPPO.png
I do not recommend this when using the index table engine, as it may cause the results to be less relevant, I recommend this configuration: https://i.imgur.com/W8pYVDD.png
If you change back the priorities to 100 on all items, you should start seeing much more relevant results in more relevant order.Best,
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