For what it's worth, I think that if those primitives 54 and 554 fail sometimes, then they can perhaps be added in a Test framework (perhaps those Tests were already written) - the "Run Tests" in Squeak. For example I can see that for some other "float" bug there is such a test : testZeroRaisedToNegativePower "this is a test related to http://bugs.squeak.org/view.php?id=6781" (there is also a method testTimesTwoPowerGradualUnderflow in KernelTests-Numbers -> FloatTest -> test - arithmetic.
Ideally I think the Squeak kernel should have some configuration option to be able to use the system provided libmath (or not) so that it's possible to choose which one , when compiling/building the VM.