St John Maximovitch is widely venerated among those of the Slavic Churches. Veneration of St Raphael Hawaweeny is less common among Catholics, although you will find some Melkites with a private devotion to him. And, yes, veneration of post-Schism Orthodox Saints is fine and not uncommon; one will also occasionally find Orthodox veneration of post-Schism Catholic Saints.
Back in 2005, the much beloved Metropolitan Nicholas, of blessed memory, Metropolitan of the American Carpatho-Russian Orthodox Diocese of Johnstown proclaimed that the second Sunday after each Pentecost “shall be celebrated as the Synaxis of the Carpatho-Rusyn Saints.” He included Blessed Pavel Gojdic and Blessed Teodor Romzha, recognizing them for their “holiness, witness and supreme sacrifice for the Christian faith and for the Rusyn people.”