yes this is true for SphericalPlot3D.
But original Inverse Kinematics Calculations are wrong. If you enter 5cm change in x,y z or correctly x,z,y direction
you get the following results :
{PoseLegLengths[{0, 0, 0, 0, 0, 0}], PoseLegLengths[{0.05, 0, 0, 0, 0, 0}]}
{{0.17035, 0.17035, 0.17035, 0.17035, 0.17035, 0.17035},
{0.155246, 0.19491, 0.180185, 0.180185, 0.19491, 0.155246}}
{PoseLegLengths[{0, 0, 0, 0, 0, 0}], PoseLegLengths[{0, 0.05, 0, 0, 0, 0}]}
{{0.17035, 0.17035, 0.17035, 0.17035, 0.17035, 0.17035}, {0.215683,
0.215683, 0.215683, 0.215683, 0.215683, 0.215683}}
{PoseLegLengths[{0, 0, 0, 0, 0, 0}], PoseLegLengths[{0, 0, 0.05, 0, 0, 0}]}
{0.17035, 0.17035, 0.17035, 0.17035, 0.17035, 0.17035}, {0.186301, 0.16337, 0.1533, 0.198841, 0.190654, 0.168317}}
and changing [Theta], [Phi], [Tau]_} angels 10 degree
{PoseLegLengths[{0, 0, 0, 0, 0, 0}], PoseLegLengths[{0, 0, 0, 10 \[Degree], 0, 0}]}
{{0.17035, 0.17035, 0.17035, 0.17035, 0.17035, 0.17035}, {0.160146,
0.166254, 0.185371, 0.185371, 0.166254, 0.160146}}
{PoseLegLengths[{0, 0, 0, 0, 0, 0}], PoseLegLengths[{0, 0, 0, 0, 10 \[Degree], 0}]}
{{0.17035, 0.17035, 0.17035, 0.17035, 0.17035, 0.17035}, {0.17035,
0.17035, 0.17035, 0.17035, 0.17035, 0.17035}} CALCULATION ERROR
{PoseLegLengths[{0, 0, 0, 0, 0, 0}], PoseLegLengths[{0, 0, 0, 0, 0, 10 \[Degree]}]}
As one can immediately notice, only [Phi] calculation gives the result for Zero Degree.
Any Ideas
Mario