By writing to sidefx, I finally understand what need to be done to export these data correctly.
There is a flag at the object level that need to be checked. Once check it will see you polymesh as a subdmesh and convert your creaseweight attribute the way katana is expecting it.
Need to test the process more in depth, but seems to be the solution.
I'm just writing this to here, in a hope, that others will find this via google search or other.
So I was trying to export creasing / creases to maya with alembic. I tried everything. But this, this solved it!
It would be nice, to have this on the actual alembic export rop, not to need to go obj level, and search for a hidden attribute.
Anyway, huge thanks for this!