"活动议案通过者" can be translated into English as "those who passed the motion for the event" or, in a more concise and context-appropriate way, "approvers of the event proposal" (though "approvers" might not be the most common word in this context, it conveys the meaning; a more natural alternative could be "those who approved the event motion/plan").
For a more formal and precise translation, especially in a business or organizational setting, you might say:
"The individuals who voted in favor of the event proposal"
"Those who supported the passage of the event motion"
However, if you're looking for a direct and relatively concise translation, "approvers of the event plan/motion" (with the understanding that "approvers" is used here to convey the idea of those who gave their approval, even if it's not a strictly defined term) or simply "those who approved the event proposal" would work well in many contexts.
A very straightforward and commonly used phrase in English meetings and discussions would be:
"The supporters/backers of the event motion" (though "backers" might imply more financial or active support, "supporters" is more general)
"Those who voted for the event proposal" (this directly indicates that they were part of the decision-making process and supported the proposal)
Given the options, "those who approved the event proposal" is likely the most accurate and widely understood translation.