Yeah, it’s just a tricky location after all, really. Another thing people have tried is shimming on the whole brain first with first-order shims only (with GRE or Brain) and then only shim the MRS volume with the higher-order shims. (I believe that’s in one of the linked threads above)
Other than that, try placing the sat bands (set to the frequency of water instead of lipids) very specifically over the sinuses i.e. behind the forehead and below the frontal lobe.
Did you see the gradient polarity settings? I believe they are these:
Try various permutations of RL, AP and FH (yes there are a lot of permutations to trial - you can shorten the acquisitions to see if one combination gets rid of the out-of-voxel echoes)
There’s not much else I can think of.