First of all, you need to know that you’re not creating tag HTML. HTML is just what was defined by W3C with this nomenclature. HTML is a default that does not allow customization. You are creating tags XML that browsers accept joint use by liberality of interpretation allowing it to interact with the DOM in whatever it needs.
It could even be a public site if you need indexing, just know that some browsers may not understand this well (it can’t be very old, like IE8).
You need to know how to do it right. By example it seems you know, except for the names used.
It may suffer a little with most of the development aid tools that will complain of "their" tags. This is an incompatibility (because of them, not your).
Maybe in the future a tag HTML pattern that uses the same name as used. You will have to make a global renaming from yours to something else. ls that okay with you? To avoid this it is recommended that the name of your customized always have a dash (minus sign) in the name.
Within those conditions everything is ok. Go deep!
Documentation. Draft of technology. JS useful.
Interesting tutorial on the subject.
If you want to create custom tags, pq does not part pro XML ?
– MagicHat