homogenous equations

why are equations not true even when homogenous?

Because being homogeneous is not the only criteria for being correct.
All you can actually state is that if an equation is not homogeneous it cannot be true.

If it is homogeneous, all that is saying is that the units of the quantities agree on both sides. It doesn't say anything about whether the equation correctly expresses the relationship between the quantities.

The formula for the area of a circle would be homogeneous if it was A = r² but it would't be correct without the Pi, would it?

there was a
question in a paper referring to why this is so ?

So what exactly did the question ask?

An equation can have any number of correct or incorrect dimensionless constants in it and still be homogeneous.

F = ma
F = 2ma
E = mc²
E = 5mc²
K.E. = ½mv²
K.E. = ¾mv²

All the above are homogeneous.