Not sure if anyone else uses Plumber, it’s a QoL addon (and I can’t even remember what I got it for!), but it has some neat housing features too, like macroing the house hearth to your action bars.
I just recently noticed their latest update allows you to select which house you want to hearth to, so I can go to my ally or horde house with a button click.
Has this always been a thing outside of the addon? I haven’t found any other way to do it other than use the bugged housing portal.
You can choose which house you want to interact with in the upper right corner of the default housing UI. There is a small drop down.
I never realized that was to change the hearth location too, I thought it was just to change the UI for the house level. I never had to hearth to my horde home on my alliance character, so I never clicked it 
I learned quickly during early release. It always defaulted to my Horde house so I had to change it every single time I wanted to use the hearth. Actually deleted my Horde house for a while because I got tired of always changing it.
Good to know!