As said, this equation will not show any explicit solution.
However, you could notice that the equation $$f(x,a)=-e^x \ln \left( \frac{(e^x -2 a)(1+a)}{1-a} \right) + xe^x +2a e^x - 4 a^2 - 2a = 0 $$ has two roots in $x$ for given $a$ and one of them (apparently the largest one) seems to be close to $a$ (just smaller than $a$). Expanding $f(x,a)$ as a Taylor series built at $x=a$, $$f(a,a)\approx \frac{4 a^4}{3}-\frac{2 a^5}{3}+O\left(a^6\right)$$ So, Newton method starting at $x_0=a$ would quickly converge to the root.