JSON Map Markers - Rule could not be applied.

[SundayReds]

I'm trying to convert PrivateEye's quest mod Tools of Kagrenac. It has no stated dependency on SKSE or anything troublesome (at least other than the base game itself).

Everything converts properly except the single json file containing map markers. Message as follows:

Could not apply rule for <MapMarkers\tools of kagrenac.json>

I'm not too familiar with how mods put in / modify vanilla map markers. Should I be concerned?