The problem is within fact, that in European Escalation, account progress is stored localy on your PC, normaly on Steam this should not be an issue (as Steam actualy saves to cloud even your graphic settings). Under certain condition, this process can be disturbed via user.
However, never heard of this issue before, and I did even couple clean OS reinstalls on my PC - try to enable syncrhronisation of the game in Steam setting, as well as auto-update - and use Cloud files, instead local ones, if asked. Steam should then download your "account-file" - IF you had sync on BEFORE reinstall. In case you had sync off - well there still can be file with your profile saved within Documents, (something like Eugen-Wargame1-XXX), but I wonder why it would cooperate with the game already.
Worst scenario for you : you re-downloaded the game with sync-off, started game, loged-in found no stars, exited game, allowed sync. There Steam asked you whether use your new local files, or the "old" from cloud. In case you selected using local files ("new") . you have overwritten the cloud save with empty profile file. Then you have to replay the glorious campaign again as you deliberately lost the progress (though unintentionaly).
Moving or deleting local files WHILE havinf sync off is a manual way how to completely restart EE campaign - I do that sometimes on my Linux partition with GoG Wg:EE installed on. That is why I know
For your health, I hope you play EE in solo campaign, so actualy you can only replay it "under stock conditions" - but in case you play online with it, I realy feel sorry for your stars/units loss...