I would second most of what has been said, LGH. This recipe was clearly developed for active dry yeast, and even then the amount used was excessive. The baker who switched to instant yeast didn’t know to use way less instant for the same result. Also, you don’t have to hydrate instant yeast (the 10 minute soak in warm water with sugar until it froths). You mix instant yeast in with the dry ingredients before adding the liquid.
This is not a particularly lean dough. Not having any prefermented dough ingredient like a biga or sourdough, it would have to rely on a little butter and sweetener plus the rosemary to give it flavour. Otherwise it’s “just plain white” and not a white with much depth of character. The amounts need to be kept very small, however, or they’ll create the characteristics you’re trying to avoid. No more than a teaspoon each of butter and sugar. Rather than honey for an alternate sweetener, known for its moisture retaining properties, maybe malt powder? Or barley malt syrup, if you can’t find powder. Use 1/4 tsp of the powder or 1 tsp, if it’s the syrup.
Definitely bread flour! Or if you have access to an unbleached AP that has 13% protein (gluten), you can use that. This gives the bread its structure. Freshkid’s comments on water temp are right on! Again, warm water would have been needed for active dry yeast, but it kills the instant dry. I also find that even with a 10 to 20 minute rest after the initial mix, bread dough is not sufficiently developed in my stand mixer until a total of 8 to 9 minutes kneading time. The blistered look of your crust suggests an underdeveloped dough. Also that it may have risen too much after shaping. Take it to “almost double” in volume. You want to have some oomph left, so the bread can continue to rise in the first few minutes of the bake (oven spring).
Yes to high initial heat - at least 400. I’d try 420 first. Steam in the first few minutes is very useful to develop a good crust. Even spritzing the inside of your oven with a spray bottle of water after you load the bread will help. Spray once again, 4 or 5 minutes later. Around the 10 minute mark, you can lower the temp to 375 if the bread is browning too quickly. Even with the initial higher temp, I’d say you need to bake your bread longer. Thump the bottom of one loaf, and listen for a pronounced hollow sound. Also press the side walls, which should feel firm. Tuck the loaves back in the oven if there’s any give at all. Above all for the softness issue, don’t store your bread in plastic bags.
Good luck! Let us know how you get on.