Does the supermassive black holes inside the Milky Way still "burp" or
it is already cured
Technically, black holes don't burp it's the material that falls into a black hole, as it gets tightly squeezed and under enormous spiral and magnetic forces it shoots out gamma rays at the poles perpendicular to the accretion disk. More details here.
The super-massive black hole (not holes as there's just one) in the center of the milky way isn't currently "burping" but the next time it eats a star it's expected to "burp" again. I remember reading that this may happen sometime in the next 10,000 years or so, but I couldn't find the article just now.
"Burping" or Jets of material are more active when galaxies are young. The quasars observed by large telescope operate in that way.
I like to think that a supermassive black hole that "burps" lies in
the core of every spiral galaxies. Am I mistaken?
This is essentially correct. Quoting this article
Astronomers believe that supermassive black holes lie at the center of
virtually all large galaxies
Black holes are surprisingly good at shooting material back into space, strange as that may sound. Source.