Usual notice that I don’t work for BALG or have any involvement in their business, but I don’t think I’ve ever heard of any e-commerce site where the basket reserves an item, because people get that far then drop out, or change their minds, or whatever, so I strongly doubt that myself, but that’s just my opinion as someone who shops online.
Baskets that do reserve items usually have a time limit set, for example if you book online gorcery delivery in the UK, one “product” you also add is the delivery time-slot, and that will usually be reserved for like 1 or 2 hours max, and if you fail to checkout and complete payment then you lose the slot because those are in limited supply.
I don’t know much about that product and don’t have time to dig around but if it’s limited edition, it probably won’t be reserved for you - but yeah, the help desk are the final authority on this obviously, just weighing in with other examples in case that helps.