对于任何试图这样做的人来说，这是我想出的最终解决方案：

var entities = require('@jetbrains/youtrack-scripting-api/entities');
var workflow = require('@jetbrains/youtrack-scripting-api/workflow');

exports.rule = entities.Issue.onChange({
  title: 'Support_bug_resolved',
  guard: (ctx) => {
    const logger = new Logger(ctx.traceEnabled);
 
    const thisIssue = ctx.issue;

    function checkFieldState() {
      //check that state is changing from closed to resolved
      return thisIssue.fields.isChanged(ctx.BugState) &&     thisIssue.fields.was(ctx.BugState, ctx.BugState.Resolved) && thisIssue.fields.becomes(ctx.BugState, ctx.BugState.Closed);
   }

    function hasLinkedSupportIssue() {
      //Check we have a linked issue from the support project
      return thisIssue.links["helpdesk log affected by"] != 0;
    }

    function checkFieldFn() {
      var check = checkFieldState();
      var hasLink = hasLinkedSupportIssue();
      return check && hasLink;
    };

   try {
      return checkFieldFn();
    } catch (err) {
      logger.error(err.message);
    }
  },
  action: function(ctx) {        
    const logger = new Logger(ctx.traceEnabled);
    
    const thisIssue = ctx.issue;  
    //Get the first linked support issue - we assume there is always only one
    const supportIssue = thisIssue.links['helpdesk log affected by'].first();

    try {
      //If the current state of the linked issue is 'Awaitingfix', make it 'ActionRequired'
      if(supportIssue.State.name == "AwaitingFix") {
        supportIssue.State = ctx.SupportState.ActionRequired;
      }
    } catch(err) {
      logger.error(err.message);
    }
    
    
  },
  requirements: {
    BugState: {
      name: "State",
      type: entities.State.fieldType,
      Resolved: {name: "Resolved"},
      Closed: {name: "Closed"}
    },
    SupportState: {
      name: "State",
      type: entities.State.fieldType,
      AwaitingFix: {name: "AwaitingFix"},
      ActionRequired: {name: "ActionRequired"}
    }
  }
});

function Logger(useDebug = true) {
  return {
    log: (...args) => useDebug && console.log(...args),
    warn: (...args) => useDebug && console.warn(...args),
    error: (...args) => useDebug && console.error(...args)
  }
}