Some Romans believe that when the apparition talks of "conversion of Russia" it means specifically conversion to Roman Catholicism. From a RC it makes sense, since from their stand we are a heresy and heretics have to convert to the true church. The concept that it is enough to believe in Christ is Protestant, not Orthodox or Roman. If one "believes in Christ" but is not a member of His Church, first, he does not fully believe, second he is not even baptized, despite whatever rite was performed.
Other Romans though, and the Orthodox who actually venerate the apparition, believe that it is conversion in the OT sense, where many times we see God speaking of the conversion of the enemies of the Jews meaning that they would stop being enemies or at least become peaceful and not that they would become Jews.
Also the apparition spoke of the "errors of Russia" not of communism in particular. Due to the "timing" of the apparition, obviously the radical socialist doctrine is the foremost one she was addressing, but some RC think that Russia will be the source of several errors until the day the Pope consacrates Russia to the Immaculate Heart of Mary *and* the RC faithful attend communion on every first saturday of the month (this second part of the condition is often forgotten). Of course, some include Orthodoxy as some of the errors that Russia would spread. Again, from that perspective, the current trend to support Orthodoxy is just one more case of "Russia spreading its errors".
Here is the text in Portuguese where the apparition makes the request:
"Se fizerem o que eu disser salvar-se-ão muitas almas e terão paz. A guerra vai acabar, mas se não deixarem de ofender a Deus, no reinado de Pio XI começará outra pior. Quando virdes uma noite, alumiada por uma luz desconhecida, sabei que é o grande sinal que Deus vos dá de que vai a punir o mundo dos seus crimes, por meio da guerra, da fome e de perseguições à Igreja e ao Santo Padre. Para a impedir virei pedir a consagração da Rússia a meu Imaculado Coração e a comunhão reparadora nos primeiros sábados. Se atenderem a meus pedidos, a Rússia se converterá e terão paz, se não, espalhará seus erros pelo mundo, promovendo guerras e perseguições à Igreja, os bons serão martirizados, o Santo Padre terá muito que sofrer, várias nações serão aniquiladas, por fim o meu Imaculado Coração triunfará. O Santo Padre consagrar-me-á a Rússia, que se converterá, e será concedido ao mundo algum tempo de paz".http://www.cancaonova.com/cnova/dicas_fe/segr_fatima.html
"If you do what I said, many souls will be saved and there will be peace. War will be over, but if you do not stop offending God, another worse war will come in the reign of Pio XI. When you see a night enlightened by an unknown light, know this is the great sign that God gives you that He is going to punish the world for its crimes, through war, starvation and persecutions to the Church and the Holy Father. To prevent this, I will come request the consacration of Russia to my Immaculate Heart, and the redeeming communion on first saturdays. If you give me my requests, Russia will convert and you will have peace, if not, she will spread her errors to the world, promoting wars and persecution to the Church, the good ones will be martyrs, the Holy Father will have much to suffer, various nations will be annihilated , but in the end, my Immaculate Heart will triumph. The Holy Father will consacrate Russia to me, she will convert, and the world will have peace for some time."