@ darij grinberg: Due to the low quality of the scanned file, OCR will produce lots of mistakes (and this brings trouble if you were using google translation). BTW, it will not cost too much if ZBMATH could at least make the "reviewer's name" searchable.

@ Alexandre Eremenko: If the database is sold as "a product", then they could surely improve its quality, say, using more clear files. Some reviews are written by true experts and hence useful to other math workers. Simply uploading non-searchable scanned files greatly reduced its function.

@user64494 "Free access is limited to 3 results, and filter functions are disabled. For full access subscription is required."