Nobody had a birth certificate those times ( I mean in Russia) .
They had the church books, where there was a written line that ........ daughter of .......... was born at .....
and was baptized at ...... in ...... the name of God Parents are .....
Then when children had to go to school , or if it will be needed for a salary of the father, parents went to Church , have got the copy from Metrical Book , then they went to the notary and have got the Certificate.
Certicitate confirmed the text of Metrical Book and had a stamp of a notary and its sign. but it was just A4 paper.
Maybe if Alix attented some schools of courses , she needed Certificate.
Maybe she needed it in order to get the passport.
I do not know if Romanovs had passports?