### Chinese: 伊核协议相关方今年4月开始在奥地利首都维也纳举行会谈，讨论美伊两国恢复履约问题。
### English: The parties to the Iran nuclear deal started to hold talks in Vienna, the capital of Austria, in April this year to discuss the recovery of the United States and Iran.
### Errors: There is a major error of incorrect translation has stylistic problems at "recovery of the United States and Iran". There is a minor error of incorrect translation is missing content from the correct translation at "in April this year".

### Improved English: Related parties of the Iran nuclear agreement started hosting talks in Vienna, the capital of Austria, since this April, to discuss the problem of restoring honoring the agreement by the US and Iran.