Count Fréedéricksz died on July 1st 1927. You used the wrong sources for your conclusion. Finnish newspaper informed about his death on July 3rd 1927. But in your article are many more mistakes, for example this one: "After Nikolai II appointed Vladimir Borisovich the Minister of the Imperial Court on April 5 1889 ... " Wrong date, besides in 1889 Alexander III was still Tsar.
Also Fréedéricksz arrived in Finland in 1925, not 1921.
You write: "However, there is one more component, which conceivably provides the most poignant conclusion to Count Vladimir Frederiks' life story. Even though Vladimir Voyeikov's name appears on the left hand side of the gravestone as 'Wladimir Woyeikov', Vladimir Frederiks' surname was etched on the front using the Swedish surname 'Freedericksz', thereby informing those who cared to visit the gravesite that in death the Russian Count was acknowledged as having Swedish ancestry."
I am one, "who care to visit the gravesite", often so. Vladimir Voyeikov's name is on the right hand side of the gravestone. On the left hand site is Eugenie Woyeikow's name.
On the front side Count Fréedéricksz name is just as it is registered in the House of Nobility. He was a Finn all his life, and that was the way his Finnish name was written. On his gravestone nor he, nor his daughters had to acknowledge that the Count in death had Swedish ancestry. A most poignant conclusion.
And yes, the gravestone has July 1st 1927 as date of death....
About the period 1866-1870 you write: There are no details found that reveal the reason for the lengthy absence from active duty." That means, you did not find them. He was in Paris, where both his daughters were born, Eugene in 1867, Emma in 1869.