Dual national traveling to Indonesia, can I use my Albanian to leave my country and my South African passport to enter Indonesia? [duplicate]

Many countries actually require that you leave and enter the country with that country's passport. So that takes care of leaving Albania.

After that, you can use your RSA passport -- as long as the name is the same -- and travel all the way to Indonesia, and back. Moreover, when you leave Singapore back to Germany and Albania, you might have to show both passports, as RSA citizens might not have free entry to Albania. But that's no biggie, as airlines are used to dual citizens.

Finally, a remark on arriving in Indonesia. You don't need a visa on arrival: both RSA and Albania are on the visa waiver list for tourism. As long as you're going to Indonesia for tourism, both of your passports will work, and you won't need to get a visa.