I'm not sure I understand your question - the gate is attached to the wall and is mapped both as a way and a node. As far as I can tell this is mapped according to how the wiki expects it (https://wiki.openstreetmap.org/wiki/Tag:barrier=gate).

I'm not great with JSOM but this is a warning saying we shouldn't have the same tags on the node AND the way (ref https://josm.openstreetmap.de/ticket/7639). Makes sense for some things like the example in the ticket but sounds like an unintended bug here as I'm not sure routers will look at intersecting ways when looking at access tags. I can try and raise a ticket with JSOM if you want?