Everywhere in the world the spelling of names evolves with time and especially migration. Think of all the Americans whose names were 'chosen' by immigration clerks at Ellis Island who couldn't manage the Polish, Russian or German spellings. Many people also chose to anglicise their names to appear less foreign.
My own surname has a Y at the end which is a clear attempt to make it appear more English. It might have been a British colonial official trying to make sense of a foreign name, or an ancestor trying to blend in. You get that in the DR with surnames of Italian origin like Alberti which are spelt 'Alberty'. Where I come from there are lots of people called Parody, which is very silly indeed. The original Italian surname is Parodi, but I guess some people thought 'Parody' looked more English!
In the DR you come across this sort of thing quite a lot: adaptations of French surnames like Du Prez (Dipre) that probably arrived here via Haiti, English surnames like Barrett (Baret) and so on. It's bound to happen when there is such a strong oral culture and a relatively weak written tradition, until recently at least.
I think I've mentioned before the friend who has a name that looks like a typo because the person who wrote out his birth certificate was dyslexic, and his parents weren't paying enough attention! He goes by the name his parents chose in everyday life, but in official documents he has to use the name as it appears on the birth certificate.
The Gracesqui name could be Polish (and there are some Polish Jewish names here that pre-date the Jewish immigrants of the 1940s), French, or something completely different. If you know which part of the country your grandparent was from you could try the parish records for birth, marriage and death certificates.
I know my husband got pretty good results this way while researching his family tree in search of the famous Guzman inheritance. BTW he is eligible, so when it comes through, the drinks are on him.