See if this makes a difference. I usually build my 'To:' and 'Cc:' fields outside the email object which makes it easier to read and understand 2-3 years from now.. your future self will appreciate it! lol
for (var i = 0; i < data.length-1; ++i) { //open for
var row = data[i];
var link = row[28];
var emailAddress = row[29];
var director = row[33];
Logger.log(director);
var manager = row[34];
Logger.log(manager);
var htmlBody2 = "Dear Provider,";
var emailSent = row[30];
var cc = `
em...@thisaddress.org, ${manager}, ${director}`; //or even:
var cc = `
em...@thisaddress.org, ${
row[34] }, ${
row[33] }`;
if (emailSent === '' && emailAddress !== '') { //open if
GmailApp.sendEmail(emailAddress, subject, '', { //open object //I assume the subject is defined above somewhere
htmlBody: htmlBody2,
cc: cc
}) //close object
} //close if
} //close for