I'd like to have a tool for monitoring changes in OpenStreetMap (OSM) for tags only, not geometry. For instance, I'm interested in detecting any tag changes regarding one-ways in streets. This can be the 1) suppression of the tag oneway=*, 2) the modification of the value of the key (oneway:yes -> oneway:no), 3) the addition of a tag oneway=* to a highway, or 4) the creation of a new object tagged with oneway=* (the latter including the creation of a new geometry).

For now, I'm using a overpass query using the adiffargument, as e.g.:

[out:json][timeout:250][adiff:"2017-01-01T00:00:00Z","2017-09-01T00:00:00Z"];
{{geocodeArea:Ixelles}}->.searchArea; 
(
    way["oneway"](area.searchArea); 
);  
out meta;
>;  
out skel qt;

This query shows me all the changes associated to any objects tagged with oneway=* in my search area between the 2 dates. The problem is that I have a lot of false positives which are not strictly related to the oneway tags: addition of other tags (eg; surface=*), slight changes in the geometry like node alignments, etc.

How can I detect the changes that are only related to the tag "oneway"?

Thanks in advance.