No, refering to him as "grandson" will not invalidate the will, if it is clear from the will who is being referred to (i.e. he is also identified by name): any reasonable court would conclude that referring to him as "grandson" is nothing more than an experession of affection or of the closeness of the relationship. Courts will also not invalidate a will for a typo, like a misspelling, the issues you describe do not, by themselves, invalidate anything.If you can show the will was forged, or that your grandmother was coereced or tricked into signing a will, that would be different: those facts can certainly invalidat a will. But you need much more than the errors you describe to show those things.