Hi JMF,
I would look at the liver enzymes given that Rifampin is CYP3A4 inducer. I think most drug interactions with Rifampin is actually because it very strongly induces CYP3A4 (up to 90%).
I don't know about
cryptolepis but it looks like Houttuynia is a CYP3A4 inhibitor:
"The most potent plant, with respect to inhibitory effect on CYP3A4, was found to be Chrysanthemum morifolium with an IC50 of 95.7 (μg/ml). It was followed closely by dandelion (Taraxacum mongolicum), liquorice (Glycyrrhiza ularensis) and bishop's weed (Houttuynia cordata), which were approximately1.5 times less potent than chrysanthemum. Field mint (Mentha haplocalyx) and Japanese honeysuckle (Lonicera japonica) were found to be 10–15 times less potent than chrysanthemum."
https://academic.oup.com/jpp/article/66/10/1478/6128004On the other hand Artemisinin is also a CYP3A4
inducer:
https://pubmed.ncbi.nlm.nih.gov/10583023/So in short, given that you have been tolerating Rifampin so far, I would personally go slow with the herbs and see what happens.
Generally speaking you don't want to take a substrate with an inhibitor.
Here's some more information on how it works:
"Drugs that cause CYP450 drug interactions are referred to as either inhibitors or inducers. An inducing agent can increase the rate of another drug's metabolism by as much as two- to threefold that develops over a period of a week. When an inducing agent is prescribed with another medication, the dosage of the other medication may need to be adjusted since the rate of metabolism is increased and the effect of the medication reduced. This can lead to a therapeutic failure of the medication. Conversely, if a medication is taken with an agent that inhibits its metabolism, then the drug level can rise and possibly result in a harmful or adverse effect. Information regarding a drug's CYP450 metabolism and its potential for inhibition or induction can be found on the drug label and accessed through the U.S. Food and Drug Administration (FDA) or manufacturer's websites."
https://www.drugguide.com/ddo/view/davis-drug-guide/109519/all/the_cytochrome_p450_system:_what_is_it_and_why_should_i_care_