I wouldn't like to see a speed challenge - I've seen them on the pottery throw down and I don't like the way skill goes out the window in favour of speed.
I don't think machines from the 1980s would be vastly different to current ones TBH. I learnt to sew on what I guess was a 70s machine and then 80s ones at school and both styles did the functions of a basic machine now.
Bags would definitely work as a challenge. Curtains are basically a rectangle with some tape at the top so perhaps not technical enough... I think a lot of soft furnishings probably fall under the "too easy" category.
What men's clothing have they had this series? The rugby shirt and holiday shirt... is that all? They've made ties, pyjamas, kilts, waistcoats (I think) and some other tailored item in the past. The bias is definitely towards women's clothing - is it perhaps more complicated and shaped?
I used to do tailor's tacks (and still do when I need to make the point of a dart, which is rarely!) My parents had a gadget that did them for you - you pushed it in through the fabric caught the end of the thread and pulled it back out again.
I vaguely recall tacking rather than pinning at school but when my dad taught me to sew before then he definitely used pins.
Embroidery I only did in primary school (Y6) and at Girls Brigade on Binka. I have a felt owl upstairs that I made at primary and it has embroidery on the chest bit and, I think, around the eyes.
DD (and DS's) have done nothing like this. DD showed some interest once but it died off.