Unless we're talking about something truly enterprise (Magento at 4 million lines of PHP dependency injected MVVC hell comes to mind) or very obtuse (hiring ocaml devs to work on their compiler) senior means senior engineer, I don't care what you worked on to be honest. Senior perl engineers can flip to ruby in month and be totally proficient. A good Java programmer with 10 years experience will have plenty to bring to the table in C++ .

If you are a senior developer and haven't seen half a dozen frameworks, tool sets, or languages under your belt. What value are you in 2 years when we shift gears