I need your help with a poem!

The average native speaker of English is going to be confused by the poem, starting with   the first line. I had to reach for the dictionary, not being able to figure out what a bathysphere has to do with anything.   It's OK for a poem to stretch the reader a little, but tristfully is a word not even one in a hundred editors would know.

Translation is always difficult, and poetry us even more of a problem.   I admire your courage in attempting thus task.

I suspect you're trying to do a word-for-word translation.   You will need to take greater liberties to maintain the sense in a poetic form.

My impression is it is quite interesting. The bud is a thing that blooms into life, but does a bud ever know life?- much less death. By contrast, the flower knows both life and death. So the poem is about a clash of perspectives. The flower seems to be wiser, it laughs, and its death in the end is an affirmation that it has known life, that the secret of life includes death.

I wouldn't dare recommend modifications to a Persian-origin text for obvious reason. But I like this poem just the way it is, as an English poem. (Only 'trist' is quite a strange word to me. Maybe you want the bud to speak trustfully, or else wonderingly or naively or longingly or forlornly.)

I would appreciate if you offer any modifications that would make it better.
The Secret of Life
By Gheysar Aminpour
The bud tristfully said:
Life is
One's lips from laughter to shut,
In a corner inside oneself to squat.
The flower, said laughing:
Life is to blossom,
Secrets with a green tongue to reveal.
The discussion between the bud and the flower from the garden
Still is heard….
What do you think?
Who is really right?
I think
The flower has hinted at the secret of life;
After all, she is a flower;
The flower, a Couple of Shirts
More than the bud, has worn out!

I also find the poem interesting. I'm also not sure I get the meaning, especially in some spots. There are two overall comments I'd make for improvement.

First, you have inverted the English syntax in a few spots: (e.g. " ... One's lips from laughter to shut, / In a corner inside oneself to squat." ) While this is often done in English poetry, it is a device usually reserved because of the constraints of formal rhyming poetry. It is jarring in this blank verse. The word order seems out of place in a few spots.

Second, your level of language seems to shift. It starts off very formal and "poetic", then when I get to the lines "What do you think? / Who is really right?" I feel like I've dropped a few hundred feet into the vernacular. It is jarring, but I'm not sure it is the kind of effect you want.

I'm not sure I got all the meaning correct, since I don't know the original, but here is a rewrite to consider:

The Secret of Life
By Gheysar Aminpour

The bud sorrowfully said:
Life is
A closing of the lips from laughter to silence,
Finding a corner inside yourself to squat.
The bloom, said laughing:
Life is to blossom,
Sharing her secrets with a verdant tongue.
The backyard discussion between the bud and the bloom
can still be heard….
What are your thoughts?
Who has the answer?
I think
The blossom has whispered the secret of life.
After all, she is a bloom:
And the blossom has worn a few blouses
More than the bud, and has worn them out!

Does any of this work?

Zahra, that looks like a great way to rewrite it. I would consider it.