That just tells us that if fusion is the source of its power, the material composition of the FE sun must be rather dense to compensate. Remember, even those tiny dense Neutron stars in the Round Earth hypothesis operate by fusion.
The density of the sun can be obtained, should you have accurate measurements of mass.
As you probably already know,
density = mass/volume.
Because your FAQ fails to mention the estimated mass of your sun, we must use the following:
The ratio of the weight of a unit volume of some substance to the weight of an equal volume of a standard substance, measured under standard pressure and temperature conditions, is called specific gravity.
If the specific gravity of a liquid or solid is known, the density of the liquid or solid maybe obtained by multiplying its specific gravity by the density of water. Specific gravity and density are independent of the size of the sample under consideration and depend only on the substance of which it is made.
Specific Gravity = Density of the Substance/ Density of Water.
Rearranged, this equation becomes:
Specific Gravity x Density of Water = Density of the Substance.
Therefore, if the (RE and FE) sun is made of a majority of hydrogen (say, 75%), its density can be estimated.
You must provide the specific gravity of your sun in order to prove its stability and effect on a flat earth.