"Reactionary" doesn't mean literally "reacting to a problem", it's a political term that comes from the French revolution, referring to monarchists who became organized and motivated as a reaction against the French revolution.
It's more or less synonymous with "conservative" and "right wing" which have similar origins, although today it has more of a pejorative connotation in English, or sometimes specifically refers to people on the colloquial "far-right" who advocate for ethno-nationalism, authoritarianism, military adventurism, nativism, etc.
It's more or less synonymous with "conservative" and "right wing" which have similar origins, although today it has more of a pejorative connotation in English, or sometimes specifically refers to people on the colloquial "far-right" who advocate for ethno-nationalism, authoritarianism, military adventurism, nativism, etc.