Hi Stan, I think you're pronouncing it correctly (see-kwa-matic) but unfortunately the Google Assistant has a really hard time trying to understand it. I find it works using my voice on my phone but not very well with my Google Home.
I'm thinking of giving the Google action a new name rather than Sequematic to make it easier to use. Something like "automatic sequences" or "sequence automator". Give me a few days to set that up and I'll let you know when it's changed.