As it turns out, using the in-game dialog, it added my entry in the C:\...\EverQuest II\UI\DrumsUI\POI\custom_poi.xml file.
Code:
<Page Name="exp18_rgn_svarni_expanse">
<Icon Name="a Kyv Watcher" PathFindLocation="-665.36 109.15 46.49" PoiDescription="Kyv Watchers in area" PoiResource="mobsolo" PoiShowAlways="true" PoiType="MOBSOLO" Tooltip="a Kyv Watcher" />
</Page>
So, yeah I can now see it locally in my game but it didn't actually submit it anywhere. Perhaps that is what the in-game dialog is actually meant for?