Upvote:3
It is ok for Russian Church, historically some names, which we can find in ROC calendary, for example: Вѣра (Věra), Надѣжда (Naděžda), Любовь (Ljubovj), Боголѣпъ (Bogolěp), have an other view of their origin names, for those names they are Greek ones: Elpis, Pistis, Agapi, Theoprepios. At the time of Rus Baptial time the greek names yet used in their original view, it can be observed, for example, in cathedral of Sofia Kievan. And the reason of view transformation is that the slavic forms of the names, keeping their meaning, are more understandable for the people. The similar one yet name is the Leont, which becomes Лев (Lev).
There is the name pair, which form migrated from slavic to gree view. That is name Злата (Zlata), which became in Greek calendary as Chrisi. The name has appeared in calendary by the martys Zlata Moglenska.
So when we are seeing to the name of Свѣтлана (Světlana), the approach of appearing and using the name Fotini, was that, Wikipedia says that the name was blessed by the Synod of ROC in 1943. But I have not found confirmations of that point of view in the deeds of that Synod. And my point of view is the next. When at the end of XX century many women with the name of Světlana went to the Church, and the question on how to baptise them had arisen. So the church popes and bishops, which know the languages and tradition of namegiving in Church, just bless the equality of the names Světlana and Fotini by the meaning. Of course this reason can be applied to the time of Synod 1943.