Use different Country/Region from Family in App Store

Solution 1:

This is not possible. All Family Sharing members have to be in the same Country/Region.

As stated in this Support article:

Not all content and content types are available in all countries or regions. To share purchased content, all family members must use the same Apple ID country or region.

• https://support.apple.com/HT201085

Solution 2:

Your Apple ID is only valid for one country. You can create another free Apple ID with a Romanian billing address (and you will most probably need a Romanian payment method, see https://support.apple.com/en-us/HT202631). You can have multiple Apple IDs. The billing address associated with it determines with store you can use with it.