I changed the punctuation of the English sentence.

Shouldn't matter; in Russian "comma splice" is not an error. (And it feels weird to me that in English, it is so unaccepted.)

I can change, if it's nesessary.

Only if you believe it's necessary. If you feel OK with the current punctuation in Russian, then it can stay.

Думаю, это необязательно, ведь должно такой русской пунктуации что-то соответствовать в английском.
Для нас это нормально, в английском вот не любят его за что-то, а другой английский вариант - точка с запятой - тяжеловесен для применения в простом безыскусном диалоге, так что, думаю, сейчас вполне себе соответствие.

(in the Turkish original, from which I translated my variant, there has to be a comma rather than a period between the two sentences).

Ok. So, I'm going to remain it as is.
Period makes more stress on the question, in my opinion.

Yes, I agree with you, Selena.
BTW, I'm not sure I should have added this period in the middle. What say you, Ooney? I did accept patgfisher's suggestion, but on a second thought, I would still use a comma there. However, I usually accept native speakers' suggestions.


OFF:
to remain it as is => to leave it as is.

Thanks for the correction, Eldad.

Btw, natives often are not perfect at punctuation, if they are not professionals in something relating to the language.

A "comma splice" is not a grammar mistake the likes of wrong conjugation and has been used occasionally since way before our time, apparently. However, many people and style guides seem to dislike it so... I'm sure one would have to go far out of their way in order to argue successfully that a "comma splice" makes some sense, and a lot of research would be involved. It doesn't seem much worth it.~

According to my impression, many a time, native speakers who contribute on Tatoeba are also professionals on punctuation. Yet, not always. So, I have to see if I agree with their suggestions re punctuation. This time, it seems to me I was too quick to accept.

Maybe, they are.
I must say, I'm not a professional on punctuation even in my own language, all the more in English punctuation :)