As mentioned above, due to the large number of bronze merit medals awarded, it's not that easy to determine the manufacturer. The founder of the dynasty, Ferdinand, was a great connoisseur and pedant when it comes to decorations. He was spending great amount of money from both national budget and his liste civile on manufacturing orders and medals. His son on the other hand, was more of a pragmatic type when it comes to this bit. He was using the orders and medal rationally and the spending for their production wasn't as great as before. Several instances confirm that. For example, the medal "For Incentive to Philanthropy" with the effigy of King Ferdinand has been used for decorating throughout the reign of Boris III, probably, due to the large numbers in stock at the Chancellery. Another example is the fact that the effigy of Boris III remains the same on all decorations - Order "For Merit", medals "For Merit' and "For Life-saving", i.e. no updating of the King's effigy even after the birth of the heir to the Throne. And third example could be the so called 'incorrect' emission which you mention above. It's quite wide spread, no matter the spelling error. I assume that the reasons for it to be mass awarded and not scrapped, were purely financial.
Anyhow, the short answer to your question is: No, you cannot determine with certainty who the manufacturer of the medal actually was. You can only imply that it has been minted in Germany, as the majority of the other decorations of that period.
Plus, you are aware that the ribbon on the above image is not genuine, right?
PS: Technically, there's only one 'emission' of King Boris III merit medal.