As for Rinzai practice, I know that in some jukai ceremonies the forehead can be wetted (and it is briefly mentioned in the book Japanese Rinzai Zen Buddhism: Myoshinji, a living religion) but I've also observed many Rinzai jukai ceremonies where there was nothing like that. Then as you know, things sometimes vary from teacher to teacher/lineage to lineage, and there also might be differences between smaller ceremonies and the ones held at a Daihonzan with many people.
I can say that the explanation regarding trikaya is not something I've heard in connection to Rinzai jukai. So maybe that is more a Soto thing. And again, I think what happens in the sanzen room is (practically speaking) the empowerment in Rinzai practice, since there is the possibility to experience awakening through extraordinary means (according to the power of the teacher and the ripeness of the student)...and also shoken is the entrance into being able to undertake koan kufu and other practices closely with a teacher.
So it would be interesting to have information from one of the many Rinzai teachers you know (a nice circumstance!). If you learn anything interesting, I'd appreciate if you'd share it even by PM.
Sorry for off-topic tangent here.
That is interesting indeed.. I witnessed rinzai jukai and even asked for it, there was nothing like shasui/kanjo, but for me main point was the connection to teacher whom I appraciated so much.. Yea I may ask teachers from both inzan and takuju lineage earliest in May I guess when I have to do some translation. At the moment I live in Europe so there is no chance I could ask directly...
By the way once Akizuki Ryomin told me that Harada Sogaku commentary is highly regarded in rinzai, about jukai it would be 200-250 pages from longer commentary to Shushogi. I never asked laer anyone about it, so now I will have some point to clarify. Of course with others, Akizuki passed away... My impression with rinzai jukai was that it looked more like transmission of precepts in tendai.. but I am not sure, again
I translated some ritual texts of rinzai tradition and it looked like shukke tokudo is similar to tendai. Soto is distinctively different. I mean the text and all ritual.. also soto both jukai and sukke tokudo include prediction of buddhahood and homage to the future buddha, so it is why rinzai ritual drew my attention. Finally both traditions have exactly same source, Daikan Eno, and for some time were almost same stem... in China there are no any distinctions regarding those things, this I could check with Chinese monks and teachers