In your previous post you wrote "time is perceived as subjective" so I won't evaluate it as a mistake. What do you think?
I still have two more doubts.
1) The character's thougts flow freely without any temporal structures. (correction: .... freely in time). It lacks any syntax (better: it lacks conventional syntax) .Introductory expressions are missing.The flow of thoughts are (or is??) not ordered (Correction: the character's flow of thoughts doesn't follow a chronological or a logical formal order).
2) In the second type of interior monologue two levels of narration are present. (is this sentence possible??)
"perceived as subjective" -- yes, that's correct. I know there are other phrasings you have been dealing with that sometimes keep "as" and sometimes don't. Undoubtedly, it depends on the particular verb that is used. If you want to post all those in one post together, I'll try to straighten it out for you. Basically, it's the problem in dealing with phrasal verbs and/or idioms.
1. "freely in time" is really good phrasing -- concise, not wordy
"conventional syntax" -- yes
Subject is "flow" (singular noun,) so the verb is "is" or "does/doesn't" (singular verb forms).
The sentence you have in parentheses is better than the one that is before it.
2. Add a comma after "monologue," and the sentence is fine.