Mathematically, the 4-D universe is an upside/down pyramid. Newtonian mechanics have been shown experimentally to be wrong- there is no such thing in cosmology as "off by a little". Like the surface of the Earth which is curved right up to any point tangent to its surface, Newtonian mechanics are flat out wrong right down to zero relative speed; the system is incompatible with reality.

The Geometric Universe and GR work, they have experimental veracity, and the observed universe is best explained in more than 4-D.

Using more than four dimensions is not arbitrary, it is demanded by the evidence. In model construction, we pick and choose between an huge number of possibilities and find the one which best fits the data...and the multi-D model is in...the Newtonian model is out! Quite frankly it is all over but the shouting, and I won't deny there is plenty of that.

Best Wishes, Sam Cox