indeed , the Pyramid and Hapax take a very different approach to polyrhythms.
the Pyramid had polyrhythms/polymeters at its very heart… when it was released, Id say this was its USP, and frankly IF this is the most important aspect to you - I’d say the Pyramid is still the best (polyrhythm) sequencer out there!
the issue is, it confused SO many users (endless topics on this forum about it, or related ‘issues’).
as most users often just wanted simple polymeters (so to set the number of steps), and setting time signatures to get what they wanted just was overly complex (for thier use-case).
SO… we saw Squarp move away from this with the Hermod, and now the Hapax, to a more ‘conventional’ sequencer approach, that (frankly) suits more people - one that is more focused on polymeters.
but indeed track elasticity gets you polyrhythms, albeit by a different means.
and some have made some good suggestions, and hopefully feature requests… that perhaps the elasticity could be aided by expressing in ‘ratios’ rather than %, so help this a bit more.
overall, Id not say the Hapax as ‘really so poor’ at polyrhythms, rather it’s a different approach.
tracks running at different ‘speeds’ is a different way of looking at polyrhythms… rather than different time signatures…
so, can you get the same with hapax, as the pyramid? …sure , if you do a bit of maths (*)
could Squarp add Time Signature per track to Hapax?
thats something you will have to ask them, as a feature request via the contact form
I guess in an ideal world, they could do this, and somehow keep the reduced complexity that Hapax/Hermod have brought for the simpler use-cases.
but again, IF this is your #1 priority then Id say carry on with the pyramid, at least until it becomes clearer if this may change on the Hapax or not. (**)
(*) this is where we can see the focus shift… on the pyramid , you had to do a bit of ‘maths’ to get certain polymeter combinations… now you have to do a bit of maths on the hapax to get polyrhythms 
(**) given the maturity of the Pyramid, and the new approach taken by the Hapax.
its inevitable, that the Hapax does not have every feature of the pyramid (of vice versa), some will no doubt come in future firmware… others are just a different approach, often due to feedback from (pyramid) users.