Edit I found the mistake, see my answer below.
I am trying to evaluate the integral
$$\int_0^\infty\frac{x \ln(1+x^2)}{\sinh \pi x}\,dx=\frac{\ln 2}{3} - \log \pi - \frac{1}{2} + 6 \ln A $$
I know this integral was already evaluated in this post utilizing various different techniques. But I am trying to compute yet with another one, but due to a mistake which I cannot spot, I can´t finish. This is how I proceeded:
First note that
$$ \begin{aligned} &\frac{1}{\sinh \pi x}=\frac{2}{e^{\pi x}-1}-\frac{2}{e^{2 \pi x}-1}\\ &\frac{1}{\sinh \pi x}=\frac{2}{e^{\pi x}-1}-\frac{2e^{-\pi x}}{e^{ \pi x}-e^{-\pi x}}\\ &\frac{1}{\sinh \pi x}=\frac{2}{e^{\pi x}-1}-\frac{e^{-\pi x}}{\sinh \pi x}\\ &\frac{e^{-\pi x}+1}{\sinh \pi x}=\frac{2}{e^{\pi x}-1}\\ &\frac{1}{\sinh \pi x}=\frac{2}{(e^{\pi x}-1)(e^{-\pi x}+1)}\\ &\frac{1}{\sinh \pi x}=\frac{1}{\sinh \pi x} \qquad \blacksquare\\ \end{aligned} $$
Then consider the following more general integral, which upon letting $z \to 1$ recovers the goal integral.
$$I(z)=\int_0^\infty\frac{x \ln(z^2+x^2)}{\sinh \pi x}\,dx $$
It can be rewritten as
$$I(z)=2\int_0^\infty\frac{x \ln(z^2+x^2)}{e^{\pi x}-1}\,dx-2\int_0^\infty\frac{x \ln(z^2+x^2)}{e^{2\pi x}-1}\,dx \tag{1}$$
Differentiating $(1)$ w.r. to $z$ we obtain
$$I^{\prime}(z)=4\int_0^\infty\frac{zx }{(z^2+x^2)(e^{\pi x}-1)}\,dx-4\int_0^\infty\frac{zx }{(z^2+x^2)(e^{2\pi x}-1)}\,dx \tag{2}$$
Now recall Binet´s Integral representation for the Digamma function
$$\int_0^\infty\frac{x }{(z^2+x^2)(e^{2\pi x}-1)}\,dx=\frac{\log(z)}{2}-\frac{\psi(z)}{2}-\frac{1}{4z} \tag{3}$$
Multiplying $(3)$ by $4 \, z$
$$4\int_0^\infty\frac{zx }{(z^2+x^2)(e^{2\pi x}-1)}\,dx=2z\log(z)-2z\psi(z)-1 \tag{4}$$
Also, making the change of variable $2x \mapsto x$ and multiplying by $4z$ in $(3)$ we get
$$4\int_0^\infty\frac{zx }{(z^2+x^2)(e^{\pi x}-1)}\,dx=2z\log\left(\frac{z}{2}\right)-2z\psi\left(\frac{z}{2}\right)-2 \tag{5}$$
Plugging the R.H.S. of $(4)$ and $(5)$ back in $(2)$ we get
$$\begin{aligned} I^{\prime}(z)&=2z\log\left(\frac{z}{2}\right)-2z\psi\left(\frac{z}{2}\right)-2-2z\log(z)+2z\psi(z)+1\\ &=2\left(z\ln z-z \ln2 \right)-2z\psi\left(\frac{z}{2}\right)-2z\ln z+2 z \psi(z)-1\\ &=-2 \ln2 z -2z\psi\left(\frac{z}{2}\right)+2 z \psi(z)-1\\ \end{aligned}$$
Now integrate from $0 \,\, \text{to} \,\, z$
$$\begin{aligned} I(z)&=-2 \ln2 \int_0^zx\,dx -2\int_0^z x\psi\left(\frac{x}{2}\right)\,dx+2 \int_0^z z \psi(x)\,dx-\int_0^z \,dx\\ &=-\ln2 z^2 -2\int_0^z x\psi\left(\frac{x}{2}\right)\,dx+2 \int_0^z x \psi(x)\,dx-z \end{aligned}$$
Letting $z \to 1$
$$I(1)= -\ln2 -8\int_0^{1/2} x\psi\left(x\right)\,dx+2 \int_0^1 x \psi(x)\,dx-\ln e \tag{6}$$
The two integrals involving the Digamma function I computed as follows
$$ \begin{aligned} \int_0^1 x \psi(x)\,dx&=-\int_0^1 \ln \Gamma(x) dx\\ &=-\frac12 \ln 2 \pi \end{aligned} $$
$$ \begin{aligned} \int_0^1 x \psi\left(\frac{x}{2}\right)\,dx&=4\int_0^{1/2} x \psi(x)\,dx \qquad \left(\frac x2 \to x\right)\\ &=4\left(x\ln \Gamma(x) \Big|_0^{1/2}-\int_0^{1/2} \ln \Gamma(x) dx \right)\\ &= \ln \pi-4\left(\frac32 \ln A+\frac{5}{24}\ln 2+ \frac14 \ln \pi\right)\\ &=-\ln A^6-\frac56 \ln 2 \end{aligned} $$
where in the last one I used the result
$$\int_0^{1/2} \ln \Gamma(x) dx=\frac32 \ln A+\frac{5}{24}\ln 2+ \frac14 \ln \pi$$
Plugging back the values of the integrals in $(6)$ I got
$$\begin{aligned} I(1)&=-\ln2 +2\left(\ln A^6+\frac56 \ln 2 \right)- \ln 2 -\ln\pi-\ln e\\ &=-2\ln2 +2\ln A^6+\frac53 \ln 2 -\ln\pi -\ln e\\ \end{aligned}$$
Which does not match with the right answer.
Can someone point me where is my mistake(s)?