Questions of kind of this - what would happen if?
If Maria someday get back the Russian throne she could use few other titles which Tsars had used.
"The official titles of the Russian Emperors were: Emperor and Autocrat of all the Russias, of Moscow, Kiev, Vladimir and Novgorod, Czar of Kazan, Astrakan, Poland, Siberia and the Taurian Peninsula, Lord of Pskov, Grand Duke of Smolensk, Lithuania, Volhynia, Podoloia and Finland, Prince of Estland, Livland, Kurland, Ingermanland, Bialystok, Karelia, Iougria, Perm, Viatka, Bulgaria and other countries, Lord and Grand Duke of Nizni-Novgorod, Tchernigov, Riazan, Polotsk, Rostov, Jaroslav, Bjelozersk, Oudoria, Obdoria, Kondinia, Vitebsk and Mstislav, Ruler of the Polar Regions, Lord of the lands of Iveria, Kartalinia, Georgia, Karbardinia and Armenia, Hereditary and Supreme Lord of the Tcherkessian Princes, of the Princes of the Mountains and of others, Heir to Norway, of the Duchy Schleswig-Holstein, of Stormarn, of Dithmarschen and of Oldenburg." (from Henri van Oene's site)
Btw At the moment she use the title of Queen of the Russian Empire of Poland or smth like that. But our historian say that her climets hasn't basics becouse Polish Sejm removed Romanovs from our throne and otherside during I WW Nicholas II recognized Regency Council and resign.