China famous modern translator Yan Fu 严复 (1854-1-8－1921-10-27) define a widely acceptable translation methodologies when translate foreign literacy to mandarin, it is summaries as 信达雅.
Translated outcome must be
- 信 accurate and with integrity
- 达 conduct the message fluently
- 雅 Elegant
To fulfill above all three requirements, the translator must also mastered their own mother tongue language. Variables such as origin literacy language and the translator use of dialect are not defined.
When a Southerner Chinese translate Florence to 佛罗伦萨 , it fulfill the above requirements. Since there are many dialect in China, the later translator will use the most common version of translated naming to avoid confusion.
Nevertheless, those rules are not always follow by "late comer" or due to different ideology. I.e. many translator in mainland China doesn't follow the common terms used by Taiwan, Hong Kong.
For example, something like 阿塔兰塔 is considered very bad translation. Because 塔 means pagoda. Since Altlanta is a city, it is rather confus to name it such. On the other hand 亚特兰大 is much fluent and elegant, anyone look at the name will think about something "big" (亚特兰[大]), i.e. a city. 亚 is preferable compare to 阿/雅/涯 due to fluency , elegant and literacy habits reason.