You can say "It is instereting learning English" and you will be understood, but to a native speaker, this sentence structure will not sound natural.

“Learning English is interesting” is the way a native would convey this thought.

As for the phrase “It is no use crying over split milk.”, it is a colloquialism that translates to: <<something>> has already happened and cannot be undone so don’t waste time worrying about it, move on.

it’s similar in meaning to another idiom: “It’s water under the bridge” (it’s already passed by and gone, let it go.)

People do and can say. "It is interesting learning English" [no ? but as a statement]

or "It is interesting learning English, is it not?"

"no use crying over spilt milk' is an expression, normal grammar does not apply.

But it is still grammatically valid.

Look upon it as "over spilt milk there is no point [in] crying"

the object [spilt milk] -> no point crying it is too late you can't put it back in the container.

no point crying [the verb] -> over spilt milk [the object] it is too late you can't put it back in the container.

You can often reverse things in English, despite many grammar books and online videos saying there is only one correct way.

Hi, sunseeker,

I am not a native English speaker, but as a student, I was taught not to use two verbs in -ing form in a row.