Titles are pretty much worthless. Anyone looking to hire engineers will just completely disregard the title and instead focus on what you actually know and what you’ve actually done. Is the job worth taking? It might be.
Tell them you’re still interested but you want to know more about what you’re being asked to do. If it looks challenging, and the company looks reputable, and you’re willing to take the pay cut, I’d say go ahead.
Then again, pure front-end guys used to get the short end of the stick. Nowadays with the rise of Javascript frameworks, they can be very well paid.
If your current job doesn’t offer you the opportunity to grow, then taking a pay cut in order to have that opportunity can be a good move. But it’s not the best move. I’d take the job and immediately start looking for another one. Any company that expects you to take a pay cut to work for them is not worth taking seriously for the long-term.