Although this question is two years old, the integral was mentioned in chat recently, I evaluated it, and then found this question. Since there is no complete solution, although Hans Lundmark's suggestion is excellent and similar in nature, I am posting what I have done.
Contours
Since the integrand is even, $ \begin{align} \int_0^\infty\frac{\sin(\pi x^2)}{\sinh^2(\pi x)}\,\mathrm{d}x &=\frac12\int_{-\infty}^\infty\frac{\sin(\pi x^2)}{\sinh^2(\pi x)}\,\mathrm{d}x \end{align} $ Define $ f(z)=\frac{\cos\left(\pi z^2\right)}{\sinh(2\pi z)\sinh^2(\pi z)} $ Note that because $ f(x\pm i) =\frac{-\cos\left(\pi x^2\right)\cosh(2\pi x)\pm i\sin\left(\pi x^2\right)\sinh(2\pi x)}{\sinh(2\pi x)\sinh^2(\pi x)}\\ $ we have $ \begin{align} \int_\gamma f(z)\,\mathrm{d}z &=\int_{-\infty}^\infty\big[f(x-i)-f(x+i)\big]\,\mathrm{d}x\\ &=-2i\int_{-\infty}^\infty\frac{\sin(\pi x^2)}{\sinh^2(\pi x)}\,\mathrm{d}x\\ &=2\pi i\times\begin{array}{}\text{the sum of the residues}\\\text{inside the contour}\end{array} \end{align} $ where $\gamma$ is the contour
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Therefore, $ \int_0^\infty\frac{\sin(\pi x^2)}{\sinh^2(\pi x)}\,\mathrm{d}x =-\frac\pi2\times\begin{array}{}\text{the sum of the residues}\\\text{inside the contour}\end{array} $ Residues
near $0$ : $ \begin{align} f(z) &=\frac{\cos\left(\pi z^2\right)}{\sinh(2\pi z)\sinh^2(\pi z)}\\ &=\frac{1-\frac12\pi^2z^4+O(z^8)}{2\pi z\left(1+\frac23\pi^2z^2+O(z^4)\right)\pi^2 z^2\left(1+\frac13\pi^2z^2+O(z^4)\right)}\\ &=\frac{1-\pi^2z^2}{2\pi^3z^3}+O(z)\\[10pt] &\implies\text{residue}=-\frac1{2\pi} \end{align} $ at $\pm i/2$, use L'Hosptal : $ \begin{align} \text{residue} &=\lim_{z\to\pm i/2}\frac{(z\mp i/2)\cos\left(\pi z^2\right)}{\sinh(2\pi z)\sinh^2(\pi z)}\\ &=\frac1{2\pi\cosh(\pm\pi i)}\frac{\cos(-\pi/4)}{\sinh^2(\pm\pi i/2)}\\ &=\frac1{2\pi\cos(\pm\pi)}\frac{\sqrt2/2}{-\sin^2(\pm\pi/2)}\\[4pt] &=\frac{\sqrt2}{4\pi} \end{align} $ near $\pm i$ : $ \begin{align} f(z\pm i) &=\frac{-\cos\left(\pi z^2\right)\cosh(2\pi z)\pm i\sin\left(\pi z^2\right)\sinh(2\pi z)}{\sinh(2\pi z)\sinh^2(\pi z)}\\ &=\frac{-\left(1-\frac12\pi^2z^4+O(z^8)\right)\left(1+2\pi^2z^2+O(z^4)\right)+O(z^3)}{2\pi z\left(1+\frac23\pi^2z^2+O(z^4)\right)\pi^2 z^2\left(1+\frac13\pi^2z^2+O(z^4)\right)}\\ &=-\frac{1+\pi^2z^2}{2\pi^3z^3}+O(1)\\[10pt] &\implies\text{residue}=-\frac1{2\pi} \end{align} $ Result
Thus, $ \begin{align} \int_0^\infty\frac{\sin(\pi x^2)}{\sinh^2(\pi x)}\,\mathrm{d}x &=-\frac\pi2\left(-\frac1{2\pi}-\frac1{2\pi}+\frac{\sqrt2}{4\pi}+\frac{\sqrt2}{4\pi}\right)\\[6pt] &=\frac{2-\sqrt2}{4} \end{align} $