With limited testing I have found that iDVD works to a limited extent with High Sierra 10.13.1. I am able to create a project and save it successfully as a disc image. However, some of the themes do not work properly, particularly the animated ones that show no animation. Some themes won't display the graphics on the title page. You just get a black background or a partial graphic. Other themes will not display photos or videos inserted in the photo wells. Some of the themes seem to work O.K. I haven't yet tested all of the functions of iDVD, so can't comment on those. As far as I can tell you can create and save as a disc image totally fine with some of the themes. I have not tested sub-menus and chapters. This seems to be a High Sierra thing, as iDVD worked perfectly fine with Sierra.
Hope this helps.