This is an interesting question and it looks like the documentation does not say anything about escaping those special words. First, special arguments that can appear anywhere depend on which syntax command you use. The documentation mentiones those specials arguments at :h :syn-arguments
The :syntax commands that define syntax items take a number of arguments.
The common ones are explained here. The arguments may be given in any
order and may be mixed with patterns.
Not all commands accept all arguments. This table shows which arguments
can not be used for all commands:
contains oneline fold display extend concealends
:syntax keyword - - - - - -
:syntax match yes - yes yes yes -
:syntax region yes yes yes yes yes yes
These arguments can be used for all three commands:
As for the first question, on how to escape those special arguments, I tried using the syntax-keyword special syntax element
 and this does work:
:syntax keyword Type Eins Transparent contained
 is used to denote an optional part of a keyword, so that e.g.
Trans[parent] would define the separate keywords
Transpa, etc and by (ab-)using this, I made the syntax script work as you wanted.