Really good essay! You do a good job of drawing on your experience (especially with the example of your sister), and talking about the pros and cons. My recommendations are mostly minor grammar tweaks.
to ensure themselves
I think you might mean "assure" (as in, to convince themselves)
Even though it has some disadvantage, such as having a nostalgia feeling. The cons can never exceed the advantages
Try to combine these two sentences, to avoid fragmented sentences. (You might replace the period with a comma.)
phenomena force
To correct the subject-verb agreement, change to "forces" (phenomena = plural, so "forces").
the knowledge that is imparted by a specific country, in which the child moves to is abundant.
This sentence is a little confusing right now. Consider swapping your word choice, possibly to say: "the specific country where the child goes will impart abundant knowledge."
You might not be able to make friends in a certain country, loneliness would overwhelm you.
This is a comma splice. Consider making the sentence stronger by connecting the two phrases: "If you are not able to make friends in a certain country, then loneliness might overwhelm you."
I tally with the community,
For clarity, you might say, "I side with the community."