But then there was this: https://twitter.com/NatSecGeek/status/1273329710576152581
https://www.csis.org/analysis/rise-far-right-extremism-unite...
https://www.americanprogress.org/issues/security/reports/201...
https://www.nytimes.com/interactive/2019/04/03/world/white-e...
https://www.theatlantic.com/ideas/archive/2019/01/homegrown-...
I looked at the articles you linked to. The New York Times mentions white extremist suggesting racially motivated but also mentions international terrorism instead of domestic terrorism. Your first source attempts to define right-wing extremism as a political motivation. That said your point isn’t very clear.
If you are limiting your point to domestic US terrorism racially motivated terrorism greatly exceeds religiously motivated terrorism but the numbers are tiny either way. If you are talking internationally religiously motivated terrorism by far takes the lead when you consider that ISIS is a growing threat in Afghanistan and Pakistan and when you consider the various terrorist organizations in sub-Saharan Africa like Boko Haram.