Thanks, Davide, for the tips about isHorizontal and ->value.

Is there something similar to handle exponents in horizontal format but with coefficients in stacked format? E.g., I would like antiderivative of sqrt(x) to have TeX form \frac{2}{3} x^{3/2} rather than \frac{2}{3} x^{\frac{3}{2}}. If the exponent is stacked, then baseline of its denominator is very close to the baseline of x.