How to make my chelsea buns more doughy
Fiddling with the temperature won't help you. Reducing the baking time can help, if you are currently overbaking them, but if you are not overbaking, it will just make them underbaked. So, the question is, are you baking them right, or overbaking currently?
If you are not overbaking now, you should change the ratios, not the baking time. If you want it moist-sticky, you should increase the sugar (and maybe underbake just a tiny bit). If you want it just softer, but without getting much stickier, you should increase the fat. To reduce springiness, you should drop the strong flour and use normal flour (8-9% gluten).