As summarized at Commons:Monuments database/Images without id, ErfgoedBot has found ca 31,000 Commons file pages used at Wikipedia monument lists, where a monument template with monument ID is missing. Most of them (8500) are related to Czech monuments, as listed here. The list is updated periodically since October 2018 - however, no tool and no bot processes the findings.
As discussed here, some tool exists, but it had some problems (T206398). However, the Czech list is not affected by that problem IMHO. According to the dicussion, I'm noting that task to phabricator to be not forget.
P.S.: Commons category pages of listed monuments, lacking monument ID templates, should be processed in a similar way.