You also need an IDP: “U.S. citizens who wish to drive in Romania must have an International Driving Permit (IDP) in addition to the valid U.S. state drivers’ license (DL).” https://ro.usembassy.gov/u-s-citizen-services/additional-resources-for-u-s-citizens/driving-in-romania/

I’m confident. Not to honk my own horn… (car pun intended).

I have my US (state) driver’s license & my IDP, neither which specify manual/automatic, so there’s nothing stopping me from driving a manual legally. In Romania, from what my bf told me, if you pass your test on an automatic you can de jure only drive automatic as you have a marker on your license, but de facto you can drive whatever as there are no actual legal penalties mentioned in the law for driving a manual with a marked license.