Avogadro 1.2.0 is of a branch no longer actively maintained. Instead – and if your workflow permits – use the executables of the branch leading to Avogadro2 as available on this landing page. (For some additional functionality, you might need OpenBabel and Python, see an earlier answer.)
Check if the newer version of the program equally displays the numbers as Arabic numbers (0, 1, 2, … are only of the Latin script, which unrelated to «modern» or «old»). In case you replicate the observation, report back (including the locale the operating system of the computer used). Equally worth to check is if (perhaps accidentally) an adjustment of the default font of the operating system can resolve the use of different scripts.