Do I need printed bank statements from my bank for my Thai visa renewal, or are emailed statements acceptable?

Follow the advise of the immigration office and do not challenge it. It is clear and nothing else.

you need to get the "standard bank letter" issued by them AND you need to order the year transaction detail report

MOST offices will not take the emailed downloaded from the app print out. They want the ones the bank prints (on that paper with the perforated edges 😮 ) and the bank stamp

I would certainly GO to your immigration office well before you want the extension and ask an officer IF those downloaded/emailed print outs of your own would work because some banks take 3-5 days to get that for you