The mistake in the sentence "One speaks English here" is the use of "One" as the subject. It would be more appropriate to use "someone" or "people" instead of "One" to make the sentence more natural.
Someone who speaks dramatically could be referred to as melodramatic or theatrical.
A polyglot is someone who speaks multiple languages, often at least five or more.
A linguist is someone who studies languages. Apolyglot is someone who speaks more than 2 languages.
You could call someone who speaks two languages but not well a "basic or intermediate speaker" in both languages.
Someone who speaks directly or openly, without equivocation is someone who speaks with candor.
A declaration occurs when someone speaks forcefully.
The US President picked a famous comedian to impersonate the President. To impersonate someone, you must study their mannerisms and practice how the person speaks.
unemotional
He speaks disdainfully of you.
Expatiate is when someone speaks or writes in detail and length. A good sentence would be, the professor was surprised how expatiate her essay was.
Someone who speaks dramatically and impressively could be called a declaim or an orator.
talks poorly about someone.
2nd one
Marie speaks delicately
A linguist is someone who studies languages. Apolyglot is someone who speaks more than 2 languages.
Given that 'she speaks' fits with the rest of the sentence, yes. It is a correct form of the verb to speak.