Building Starter for Recipe - HELP!

Hi, all. I’m about to make the Norwich Sourdough bread from Wild Yeast blog, as follows:

900 g AP flour

120 g whole rye flour
600 g water at about 74F
360 g mature 100% hydration sourdough starter
23 g salt

I have made this successfully before. My second-to-last batch yielded good flavor but somewhat pale crust and little oven spring, leading me to believe that there was a combination of weak starter and overproofing. I decided to build the starter twice instead of once for the batch I made last week, and although I achieved incredible oven spring, I found it lacked the usual tang of my sourdough bread.

I built as follows:  1st build – 80 g flour (72 g AP, 8 g rye, since my starter’s routine feed is 10% rye), 80 g water, and 40 g starter = 200 g total.

After about 8 hours at room temperature, I did the 2nd build –  100 g flour (90 g AP, 10 g rye) and 100 g water  added to the 200 g ripe starter to = 400 g total. I let this 2nd build ferment at room temperature for about 9 hours before making the dough.

Admittedly I have no guideline other than recipes I have read on these forums to give me any idea of what, if any, standard percentages there are of doing this type of build before baking, and how to manipulate it to produce successful spring and tang.

If anyone knows of a link to this information, or has personal experience, I would appreciate it.

 Also – I find that many recipes use terms like the above:  ‘mature’ starter, ‘ripe’ starter, ‘active’ starter – is there any difference, and if so, what is it? Thanks!