While the 4310 mAh battery and neon joy-cons are too precise to be a guess, I would still err on the side of believing Eurogamer when it comes to clock speeds. Eurogamer has a good track records with prior hardware leaks and has a reliable way of finding them out (by talking to devs). There's no reason to believe that a Foxconn employee would have any information about clock speeds, fabrication processes or microarchitectures. They're simply shipped a finished SoC by Nintendo and assemble it together with everything else. They probably do some testing of the units once assembled, but I don't imagine it tells them these kinds of specifics.
That said, A72s or A73s would be nice
Edit: Also, as mentioned above by ElTorro, even if the clock speeds are accurate, that doesn't actually mean they'll be used in games, just that they chip can theoretically hit those speeds. Particularly with the CPU clock, which sounds unreasonably high even for A73 cores at 16nm. Nintendo may push the CPU up to higher clocks in specific scenarios (e.g. for Gamecube/Wii emulation) while retaining the 1GHz limit for games.
Good post as always!!
As much as we all want the Switch to be powerful and state of the art, its time to accept the soc is no technological marvel. It will be interesting to find out what customisations Nintendo did to the X1 though.