The archaic sound of Chinese characters is definitely different from that of modern Chinese. Even if they are all modern Chinese, the pronunciation of Putonghua and dialects is different. Even the Chinese transliteration of Buddhist scriptures and incantations is different from the original without translation, such as "Buddha" translated into "Potala". Therefore, it is inevitable that the pronunciation is not accurate.
However, this has no effect. You see, in some places, some people recite Buddha's names in dialects, while others recite Buddha's names in Mandarin, but they are all the same feeling. So the key to chanting lies in a sincere heart. As long as you are not distracted, the effect is just as good!