As always, nice to hear from you again.
It's true that Standesamt sometimes has to send documents to your home country in order to check whether they are valid or not. Sometimes they have to get in contact with local lawyers for this reason. This procedure can take quite a long time (up to several months). If you tell us where you are from, we can do some research about the verification procedure in your home country.
Officials at Standesamt will tell you which documents they need to verify and if you have to provide certified translations of your documents. It's a discretionary decision whether verification is necessary or not, which is why it's not possible to make generalized statements.