Properties have a fundamental system defect from the beginning. While Wikidata interproject links (as well as classic category wikitags in other projects) works really bidirectionally (reciprocally, complementarily), properties linking an another item work only in one direction. The inverse property needs to be created manually, So far, this defect has only been compensated for by the fact that there is a system of warnings that encourage this manual creation of inverse properties. But there is no indication on the target item page that any link points to that page and that the inverse property is missing.

This problem was reported e.g. in T51165. Related problems and some ways how to solve and treat them were suggested e.g. in T209559. A concept of "virtual properties" can be acceptable until we have fully-fledged two-way properties.

The first step can be to add a section of "virtual properties" to the Wikidata item pages. This section would be in principle the function "WhatLinksHere", but specially modified: the links should be sorted by the calling property, and the format of the list should be as similar as possible to the format of the previous section of properties. Thus, these property links should be presented as virtual inverse properties.

Such "virtual properties" should be invocable and linkable (from infoboxes etc.) in the same way as "real" (directly stated) properties.

The prospective target state should be that the properties referring from one item to an another item work realistically as bidirectional, ie that their editing or monitoring of their history can be performed in exactly the same way from both sides. Thus, it would probably be appropriate for individual connections not to be an integral part of one of the item page and its editing history, but to be managed in an autonomous indexed database. Btw. category tags in other projects can be managed in a similar way and both systems (category links and property links) can be prospectively directed to their mutual compatibility.