I'm not familiar with a "tpl" file. Did you maybe mean "tcl" file?
As for your question, "is this normal?", there are always lots of ways to do a job. Sometimes a designer has to come up with creative solutions to handle some particular need. So the question isn't really, "Is it normal?". A better question might be, "Is it efficient? Is it right? Is this the best way for us?"
We here at PHPBuilder can't know the answers to those questions without knowing (A) how things were set up in the first place and (😎 what needs and requirements you have for your site.
Sometimes complex systems are complex because you have unusual needs and the designer did the best they could with their budget and your requirements. Other times, complex systems are complex because the designer was an idiot and did the best they could with their limited knowledge and experience. It's impossible for us to know which was the case here.
So your question isn't really a PHP question or a database question. Your question is, "Why was my system set up like this and is this good or right?" The best lead you have to answer that question is to talk to the person who built it. If they aren't available, then you should hire someone to analyze your system (that's what a systems analyst does).
