There is no proper FIPJP umpire’s guide, in the sense of an official document containing case law for the FIPJP rules of petanque— an official list of precedents and rulings in cases where the written rules are unclear or unusable for some reason. There is however a web site that occasionally contains useful bits of that kind of information. I’m talking about the FFPJP (French national) Guide de l’Arbitrage (umpiring guide).
To find it, first go to the FFPJP “portal” page. In the menu at the top of the page, click on the “INFOS ARBITRAGE” heading, and then click on “Guide de l’Arbitrage”.
This will take you to the Guide de l’Arbitrage page. At the bottom of that page is a long list of what are basically memoranda by the French national umpires on various subjects. Most of these memoranda aren’t relevant to someone who is not a French player or a French umpire, but a few contain official decisions about how the rules are to be interpreted. In the picture below, for example, I’ve highlighted Annexe 24-1, which is a memo on the new FIPJP ruling about how to handle a boule thrown out-of-turn (la boule jouée par erreur).
The rightmost column is entitled à teléchargér (to download). To download a document, click on the link in that column. You will be able to download the selected document. It will be in PDF format and (of course) in French. If you don’t read French, I recommend using the DeepL automatic translator.
The Rules of Petanque 
Thank you for this pearl.
Please note that the Dutch rules committee has likewise published a document (pdf) that contains the Dutch translation of the official international rules, annotated with the interpretations and rulings of the Dutch rules committee.
You may find it following this link: https://www.nlpetanque.nl/Reglementen/RPSPlus.pdf
Again, note that the document is written in Dutch, but the DeepL translator mentioned above by Jules will most probably be useful here, as well.