Maple can't translate this valid Mathematica expression, it gives error
Error, (in MmaTranslator:-FromMma) The form, a^b^c, is found in the expression. It means either (a^b)^c or a^(b^c). Please use parentheses to clarify the meaning
But there is nothing wrong with the above expression. It is valid Mathematica expression. I found why Maple is confused. It needed a SPACE after the first x^2. So the following works in Maple
eq:=FromMma(`x^2 (a+y[x])^2 y'[x]==(1+x^2)(a^2+y[x]^2)`);
And now the error went away. But a space not needed in Mathematica. It works either way.
Maple 2016.1 on windows.