No universal inventor requirement applies. Explain the actual special or advanced knowledge acquired and how the proposed role uses it, with the other L requirements assessed separately.
Establish acquired knowledge on its own facts
Identify relevant training, work and application. Not being the creator does not answer the case by itself, just as being a routine user does not automatically establish qualifying knowledge. Hypothetical example: a seismic processing analyst runs an employer's proprietary inversion workflow, having learned it from the team that wrote it, and can tell from a residual pattern which acquisition parameter was wrong.
None of that depends on authorship. Set out the training received, the years of application, the difficulty of the problems handled and the results produced, and let the file argue from those. The mirror-image error is equally costly: long access to a system, or a licence to run it, is not by itself special or advanced knowledge, and a file resting on tenure alone tends to be tested on exactly that point.
Ask the employer what a competent new hire would need before performing the proposed duties unsupervised, and how long that would take; the honest answer either supports the claim or shows it is not there. Keep the description at the level of what this employee does, since a claim pitched at the level of the industry is not a claim about the applicant. Each of the other L conditions is assessed separately and none is satisfied by the knowledge showing.