An easy way to picture the size of the effect is to imagine trying to stand upright.
Or to measure the offset from the vertical of a weight on a string.
Standing on a child's roundabout, you would have to lean a lot towards the centre, to compensate.
And a weight on a string would swing outwards at a visible angle.
Compare that to our rotation around the Sun once a year. You can't feel anything standing up, and it would take incredibly accurate equipment to measure the deflection of the weight on the string from vertical. I don't know if it's ever been done.
Now make another jump to us circling the Milky Way once every 250 million years. I think the deflection from the vertical would never be measurable.
There is a formula for the g force, I remember it from a discussion on generating artificial gravity in space.
The one fact I remember is that if you want to generate 1g, and you want a rpm figure of less than 2 you need a craft of minimum 200m diameter. (you need to rotate slower than 2rpm to avoid any dizzyness or sick feeling)
I don't know what 1 rev per 250 million years converts to in rpm, but I doubt that your balance organs would ever detect it.
Scroll down to see the formulae.