If I have mistakenly purchased U Data Roam 10 Booster for countries eligible in U Data Roam 36/ U Data Roam 36 Booster, will I be able to use the U Data Roam 10 Booster?

No, you will not be able to utilize the roaming data allocated for U Data Roam 10 Booster as the travel destination you are in is only eligible in U Data Roam 36/ U Data Roam 36 Booster.  

However, you will be auto provisioned U Data Roam 36 upon arrival as you do not have eligible pass in active.