Could you please check these other sentences, please? Thank you.

1) I’ve just been on holiday with my family.
I’ve just gone on holiday with my family.
2) My nephews did some pirates’ games.
If you have just come back from your holiday: I was in Spain with my family for two weeks. (and not: I’ve been in Spain…..) .
3) I’ve also taken a photo with a famous footballer. (or I also took a photo..?). I ate paella. It was (not is) delicious.
4) We flew back (we travelled by air??) but the flight wasn’t too long.
During (in is a mistake?) my Christmas holiday I spent time with my family.
Sorry we haven't got in touch for two weeks.
45) Sorry we have been out of touch (is "with each other" necessary??)
6) On Christmas Eve I played some party games with my cousins and at midnight we exchanged presents.
We toasted the New Year BUT we drank a toast to the New Year.
7)Last week I got a good mark in Maths.
I did a lot of nice experiences (??) when I was on holiday.
I'm writing to tell you my experiences of the last month.

Sure! Here are the corrections and explanations for each sentence:

1) I’ve just been on holiday with my family.
Correction: I have just been on holiday with my family.
Explanation: The correction here is simply changing "I've" to "I have" as it is the full form of the contraction.

2) My nephews did some pirates’ games.
Correction: My nephews played some pirate games.
Explanation: The correction here is changing "did" to "played" and "pirates'" to "pirate" as it is the correct form of the word.

3) I’ve also taken a photo with a famous footballer. (or I also took a photo..?). I ate paella. It was (not is) delicious.
Correction: I also took a photo with a famous footballer. I ate paella. It was delicious.
Explanation: Both "I've" and "I also took" are correct depending on the context. However, "was" is the correct past tense form of "is" when describing something in the past.

4) We flew back (we traveled by air??) but the flight wasn’t too long.
Correction: We flew back (we traveled by air). The flight wasn’t too long.
Explanation: The correction here is removing the question mark after "we traveled by air." It is a statement, not a question.

During (in is a mistake?) my Christmas holiday I spent time with my family.
Correction: During my Christmas holiday, I spent time with my family.
Explanation: Both "during" and "in" can be used here, but "during" is generally more commonly used in this context.

Sorry we haven't got in touch for two weeks.
Correction: Sorry we haven't been in touch for two weeks.
Explanation: The correction here is changing "got" to "been" as it is the correct form of the verb "to be" in this sentence.

Sorry we have been out of touch (is "with each other" necessary??)
Correction: Sorry we have been out of touch.
Explanation: The phrase "with each other" is not necessary in this sentence. It can be implied and does not change the meaning of the sentence.

6) On Christmas Eve I played some party games with my cousins, and at midnight, we exchanged presents.
Correction: On Christmas Eve, I played some party games with my cousins, and at midnight, we exchanged presents.
Explanation: The correction here is adding a comma after "Christmas Eve" to separate the two clauses in the sentence.

We toasted the New Year BUT we drank a toast to the New Year.
Correction: We toasted the New Year, but we drank a toast to the New Year.
Explanation: The correction here is adding a comma after "New Year" to separate the two clauses in the sentence.

7) Last week I got a good mark in Maths.
Correction: Last week I received a good mark in Maths.
Explanation: The correction here is changing "got" to "received" as it is a more formal and suitable word to use in this context.

I did a lot of nice experiences (??) when I was on holiday.
Correction: I had a lot of nice experiences when I was on holiday.
Explanation: The correction here is changing "did" to "had" as it is the correct verb to use when referring to experiences.

I'm writing to tell you my experiences of the last month.
Correction: I'm writing to tell you about my experiences of the last month.
Explanation: The correction here is adding "about" to clarify that you are telling about your experiences, not just mentioning them.

Sure, here are the corrected sentences:

1) I just went on holiday with my family.
2) My nephews played some pirate games.
3) I also took a photo with a famous footballer. I ate paella. It was delicious.
4) We flew back, but the flight wasn't too long.
During my Christmas holiday, I spent time with my family.
5) Sorry we haven't been in touch for two weeks.
6) On Christmas Eve, I played some party games with my cousins and at midnight, we exchanged presents.
We toasted the New Year.
7) Last week, I got a good grade in Math.
I had a lot of nice experiences when I was on holiday.
I'm writing to share my experiences from the last month.