The problem with the colour density of a such printed decal markings can be solved by multiprinting the same markings. Just two or three times put the same sheet through the printer. However it is better to check the way with a piece of papaer sheet of the same dimension that a clear decal sheet is. According to my experience the incorrect moving of the paper sheet at the printer paper feeding track can make markings looking washy at edges or shifted. So all has to be set accurately.