This led to a situation where I am familiar with the process of ASIC design, but can not look for any senior position as proficiency in industry standard-tools is a requirement.
Never take HR's word for anything, but especially technical
"requirements".
You really think that if you came from a Mentor (Siemens)
workplace, that a Cadence shop wouldn't assume you know the
general flow and allow you an "on-ramp"? If no, what's the
difference between a proprietary tool chain, and Brand X, Brand Y
commercial tools in this regard?
You're of course best off bypassing HR entirely but that would
require more of you, than simply applying to open postings.
You'd need connections made and customers satisfied, what
you -did- with those tools (popular or not) and get that story
to whoever's the actual hiring manager. Which is exactly what
HR seeks to prevent.
You could bury keywords in minuscule type font, in your resume
while not claiming proficiency; this could get you past the robo
scan, to the next stage of review where hopefully you "sell it"
based on what you have done and can do, rather than a selfie
of your tool collection. Because anyone can by tools with
money, yet many engineers provided those tools end up selling
real estate.