Some years ago, the dean of the law faculty of Thammasat University pointed me to www.krisdika.go.th, which is the website of the Office of the Council of State, ie the Cabinet, for thai laws. Of some laws, there is also an English translation on that site.
Currently, the link to the English translation of the Immigration Act on that site can be found on the page
https://www.krisdika.go.th/web/guest/translations-of-law?p_p_id=LawLibrary_TranslationLawPortlet_INSTANCE_PxcK4uLURwgR&p_p_state=normal&p_p_mode=view&_LawLibrary_TranslationLawPortlet_INSTANCE_PxcK4uLURwgR_javax.portlet.action=selectLawData&_LawLibrary_TranslationLawPortlet_INSTANCE_PxcK4uLURwgR_lawTypeName=I&_LawLibrary_TranslationLawPortlet_INSTANCE_PxcK4uLURwgR_lawTypeId=026011009&p_auth=iRsHIS9n&p_p_lifecycle=0
When it comes to procedures and rules for complying with immigration requirements, what really matters are the forms, rules and guidelines issued by the Immigration Bureau. Regarding the TM.30 discussed in this topic, much useful information has been posted here already. From experience, I would say that the "Regulation of Royal Thai Police on notification of a householder, owner or possessor of dwelling place or hotel manager, who takes in, as a resident, an alien permitted to temporary stay in the Kingdom" was published in the Royal Gazette. There is a website that has an archive of the editions of this publication but I can't remember the link at the moment, but I do remember that I gave up to try finding a particular publication on that site. @ningnong, you may want to print out the PDF document of the regulation that has been posted in this topic and see if a lawyer proclaiming to be an expert in immigration matters can give you the date and number of the relevant issue of the Royal Gazette, or even better a link to it.