Just some background.

On the engine: The Saratoga is designed for an Evolution 46 / 52 or a Saito 82. Those engines, as well as your OS 46 AX, total about 17.5 oz. (or 500 gm). So nothing unusual about the "expected" weight as compared to "actual" weight of the engine.

On CG: The manual states that the CG be at 70 mm back from the LE (range being 64 to 76 mm). You added 60 gm (about 2.1 oz) to the tail created a tail heavy (but flyable) airplane. I know that the 70 mm is a good starting point for a static CG before you test in-flight trim. What is the final CG?

On wing incidence: The tail feathers are bolted in place rather than being glued. The 2-piece wing is bolted together then the dowels on the LE are inserted into a former at the top front of the wing saddle and the rear of the wing is bolted down thru the canopy "hatch". The manual does NOT specify a desired wing or stab incidence angle. You got what they give you. So, do you have (or have access to) an incidence meter?

On elevator trim:Per manual the low rate is 22 mm and the high rate is 29 mm. The 5-6 mm up elevator is about 1/4" of trim. Where have you set the low and high rates?