The multivariable transform must be of type event.
If a condition or logprob query has multivariate symbol, then we cannot call logprob_factored on the children. Instead, we need to reassemble the query post-substitution and call self.logprob on the new query, which will take care of converting it to dnf, solving it, and factoring it again.
https://github.com/probcomp/sum-product-dsl/blob/c482341d04ef35febefc46f8821350e9236e8013/src/spn.py#L409-L413
self.logprob
on the new query, which will take care of converting it to dnf, solving it, and factoring it again.