My player (it's a solo campaign) just finished 100 Bushels of Rye, and is quite proud of the glowing coin he took from the caves. However, from my various readings, it's not clear what sort of legal, religious, and social reaction to expect from openly brandishing said coin (emanates a gentle but unnatural light).
Magic in Harn is so rare - and so hard to identify as magic even when it is present - that even a minor magical object is practically priceless. The most likely respose is someone will try to buy it off him for a few pence - or steal it. If someone with money or power finds out about it they may offer a substantial sum. After some time a mage may eventually find it and attempt to acquire.
So magic is essentially not present in society, either due to rarity or outright fear and prejudice in the populace. Why is that? Is magic so subtle that you couldn't detect it without training to know what to look for? Are mages so rare that the odds of finding true magic negligible for most people?
Harn was designed so that magic and/or the gods may not even be present. You could play a whole campaign and never find out the GM decided in the beginning that magic didn't exist and the gods aren't real.
Even if magic is present mages are rare. About 1 person in 1000 in the Shek-P'var. 640 on the entire island of Harn and roughly 200 Master mages. The odds of the average Harnian running into one is low - and lower still that they would realise it - and almost no chance they would see any real magic.
Campaigns vary widely on those details though.
Whether it actually exists or not in the world almost all believe in the gods - and many believe in magic.
I also can't find any mention of Kaldor's laws regarding magic - all mention of magic seems conspicuously absent from the Kaldor Kingdom module.
The following crimes are tried under temple law in religious courts. Only crimes against legally recognized churches are dealt with under temple law and only after the accused has been bound over by the secular authorities (likely after the appeal options have been exhausted). Temple courts must obtain secular consent to any death penalties. Temple courts often use trial by ordeal. The penalties handed out by temple courts will vary from one temple to another; the church of Peoni, for example, never causes any permanent harm to offenders. None of these are considered felonies; accusations must be made by the injured party.
A very dubious crime. Conjuring or consorting with demons, disposing of souls, casting inimical spells etc., for the purpose of unlawful personal gain. This too is something of a catch-all crime; witchcraft laws are not generally enforced in Rethem, and only intermittently in the Thardic Republic. Penalties: impalement, burning, drowning, hanging.