I've used JEuclid for rendering MathML in my Symja project (Java symbolic math system - point 4 of your list).
Maybe, that JEuclid is to slow (especially at startup) for rendering MathML on a mobile phone?
JEuclid is dependent on java.awt.image.BufferedImage and will not work in android
JMathTex is dependent on javax.swing.Icon and will not work in android.
Other alternatives for rendering math expressions with TeX:
and for re-arranging equations or as general Java math libraries: