Better forget Mathematicas Complex simplifying algorithms. For purely numerical evaluations the shortest way is direct manipulation by the operations definitions. At least one knows what one is doing:
(Just indent your code to get it pretty printed and copyable text, never use subscripts in communications)
z1 = Sqrt[5 - Sqrt[3 I]]; z2 = Pi/I - I/Pi; z3 = Exp[I] - I^E;
res0 = ComplexExpand[((z1 - z2 + z3) /.
Complex[a_, b_] :>
a - I b)/((Sqrt[#*(# /. Complex[a_, b_] :> a - I b)] &)[
z1 + z2 - z3])];
LeafCount[res0]
8973
N[res0]
0.566439 - 1.03623 I
Now we calculate using a replacement rule for complex numbers
res=((z1 - z2 + z3) /.Complex[a_, b_] :> a-I b)/
((Sqrt[#*(# /. Complex[a_, b_] :> a - I b)] &)[z1+z2-z3])
(-(-I)^E+Sqrt[5-(-1)^(1/4) Sqrt[3]]+
E^-I-I/\[Pi]-I \[Pi])/
(\[Sqrt]((I^E+Sqrt[5-(-1)^(1/4) Sqrt[3]]-E^I-I/\[Pi]-
I \[Pi]) ((-I)^E+Sqrt[5-(-1)^(1/4) Sqrt[3]]-E^-
I+I/\[Pi]+I \[Pi])))
N[res]
0.566439 - 1.03623 I
Finally one tries to get a normal algebraic expressions in many steps
ToRadicals@ FullSimplify[
Together@ ExpandAll[res] /.
{Power[a_Complex | a_?Negative, b_] :> Exp[b Log[a]]}]
$$\frac{e^{-\frac{1}{2} i (2+e \pi )} \left(\frac{1}{2} e^{\frac{i e \pi }{2}} \left(2 \pi +e^i \left(\left(\sqrt{20-(2+2 i) \sqrt{6}}-2 i \pi \right) \pi -2 i\right)\right)-e^i \pi \right)}{\sqrt{1+\pi \left(2 \left(\sin (1)-\sin \left(\frac{e \pi }{2}\right)\right)+\pi \left(-\sqrt[4]{-1} \sqrt{3}+9+\pi \left(\pi +2 \sin (1)-2 \sin \left(\frac{e \pi }{2}\right)\right)-2 \cos \left(1-\frac{e \pi }{2}\right)+\sqrt{20-(2+2 i) \sqrt{6}} \left(\cos \left(\frac{e \pi }{2}\right)-\cos (1)\right)\right)\right)}}$$
LeafCount[res2]
169
N[res2]
0.566439 - 1.03623 I
,
ComplexExpand
. $\endgroup$E
instead ofe
. I get{136/241, -(428/509)}
as the real and imaginary parts. $\endgroup$z // ComplexExpand // ReIm // N
should be sufficient $\endgroup$