Complex sentence: In addition, there are several EU states that have not yet adopted the euro, some of them have already agreed upon their coin designs however it is not know exactly when they will adopt the currency, and hence these are not yet minted.
Split into simpler sentences: In addition, there are several EU states that have not yet adopted the euro. Some of them have already agreed upon their coin designs, but it is not known exactly when they will adopt the currency, and hence these are not yet minted.