This task looks unsuitable for a site like that since these are technical papers with mathematics, one has to know enough LaTeX to be able to reproduce (arbitrary) mathematics by just reading it (N.B. tools like detexify help).

Also, a single mistake (like _ij instead of _{ij}) can change the meaning dramatically, and I would think that a random person on freelancer would care less about getting it right, and more about getting it looking like it's right (whereas someone recruited through LW is more likely to actually care about SI beyond being a source of money).