OP I am always very commercially minded and you mention having incurred a lot of costs writing the book which may mean I'm thinking of it the wrong way...
Your blurb about the book is not dynamic; it doesn't tell anyone why they would enjoy it. It sort of tentatively suggests they might, which isn't the right approach for a pitch.
As I don't feel fully clear what it's about, I can only chuck out some uninformed lines
Would you travel the world to make your dreams reality?
Peter Holbrook did just that, escaping war weary England for the King's Country, for a new life of farming/ rearing horses/artwork. (The farming might be the hardest sell here).
This rich biography of an extraordinary man illustrates how far passion will take you blah blah.
The story of a life lived across countries, eras and through personal challenges...this sort of thing helps make people think "ooh, I will read about him". It's a story for us, even though it isn't fiction.
You say language is key here, so maybe talk about the language and the importance of that within communities. Talk about art as language?
I was thinking about the book "Cave in the Snow", about an English Buddhist nun. She said of her biographer "I don't know how she made a good book out of me living in a cave" - but she has, because a remarkable person and a terrific storyteller make a great book.
Also in the kickstarter blurb - what about you? What are your achievements? How about a sample of writing from the book?
There needs to be a list of contacts to send this to. Colleges, arts orgs, anyone preserving the local history.
It sounds like you've done the labour of love bit but not the marketing.