Your findings are that ally is a bit stronger than g10 in bending and tension.
Dare say that the part in question isn't engineered particularly finely I.e wouldn't be sensitive to a weaker material (the Alu part on the bracket has survived use despite extensive corriosion indicating plenty strength margin) but if you were worried you could use a thicker piece of g10 say 25 or 30mm.
Half the density of alu so weight will be equivalent.
I think in this application its mostly the crush but accepting this isn't a rib transom I'd need to see the outboard bracket to make a better call.
Tensile and flexural stiffness (modulus) generally similar no so sure about strength but www has loads look at matweb or similar. Beware that there are hundreds of aluminium alloys with a big range of strengths. Alloys of Alu of steel have similar modulus (stiffness) but different strength properties.
Aluminium typ 70gpa modulus, steel 205gpa. Quasi isotopic woven glass like g10 maybe 25 gpa.