Simple vs Complex

https://speakerboxlite.com/project-info/95f8fce60a8fa2757fbd77a0d9201c3ed633c1b75c9aad6676257db474e4b7a9

What does this "Complex" exactly do? Why there is so huge difference? According to Simple Vented, I have nice to have speaker but when I turn on Complex I see the graph according to which I should throw out the speaker from the window. It gets even worse when tuning to t-line box. So how true are these graphs actually? I have tried to simulate same measurements with hornresp and winisd and and bassbox pro and get totally different outputs from which all three mentioned are the most similar to each other. I have tried to tune back and forth with the box sizes, ports, also with the manufacturer recommended boxes etc but when I turn on the complex calculation, it all turns to total nightmare.  

Hi. Could you please provide screenshots of comparisons to let me see what is going wrong? I see your project.