Let me get in on this boot vs. shoe question, because if anyone has any insight into my ankle problem, it'll change everything for me. I find I need very low-cut shoes because anything that touches the middle of my achilles rubs it raw within 2km.
It sounds like your ankles are simply not large enough to fill the boot's volume, allowing it to move excessively (or I am retarded and it's the exact opposite). Have you tried specifically heel lifts, (possibly on top of another insole) which will change the angle your heel sits at while filling some volume? Do you know whether your foot is generally narrow or broad (or perhaps broad in the toes but not at the ankle)? You mentioned lacing but just in case you haven't tried the heel lock (paragraph 4), it can help.
If you are a dude, do you always only try men's boots? In 9 / 10 cases I buy the lady's model of any given hiking boot even though I'm a dude because I have a very narrow ankle, meaning no matter how tight I lace a boot for men, even with liners and thick socks, there's a good chance I will still get excessive heel lift which leads to scraping - the only exception were Garmont "Ascent" (careful, they run 5mm shorter than most at equiv sizes) which I can highly recommend for people with super narrow feet and Mammut "Kento Guide High"
Finally, if you visit a big city, there may be a mountaineering store that has a machine like this which takes an exact measurement of your feet and ankle shape, allowing a clerk to suggest models that should fit very well quickly.
On the achilles thing, that shouldn't be getting rubbed. Your footwear is too small, or you're lacing it too tight imo. I've never had that problem but I think if I did it'd be because of one or both of those two reasons. Maybe try some slightly thicker socks too idk. Inserts or whatever too. I would never use shoes for anything but like a three mile round trip hike which isn't a hike at all lol. You're gonna want the support of hiking boots or BOOT boots all around if you're doing anything but short walks on semi finished service roads or hard packed dirt trails
Have you tried specifically heel lifts, (possibly on top of another insole) which will change the angle your heel sits at while filling some volume? Do you know whether your foot is generally narrow or broad (or perhaps broad in the toes but not at the ankle)?
I haven't tried heel lifts, but since low ankle cuts don't give me this problem, it seems worth a try. Is it ok to hike long distances with them? As to the width of my foot, the ankles of most brands of trainers have been ok, but the toe box is consistently a problem, so I prefer barefoot shoes.
In fact, it's a women's model that does it the worst to me, Columbia Peakfreak X2 Outdry. I got them before I knew about barefoot shoes and I can't pad them with socks because the toe box already almost rolls my foot like a cigarette, despite the length being correct. But my Sorel snowboots are unisex and sometimes scrape my ankles, too, especially if I tie them at the top, so I usually lace them halfway and wrap the laces around the ankle. I'm a woman, but I didn't think I was Peggy Hill.
You could try on either scarpa or hanwag (a brand held in pretty high regard in central Europe), both of which tend to feature roomy toeboxes in their women's shoes. Their tatra light lady is pictured in the first "Footwear" spoiler in the OP and imo it is rather broad in the front. I think you could walk 2km and just clean the sole and return it without issue, as the sole shouldn't show wear at that point, though presumably this varies by shop and some might be more troublesome than others. Do so in the afternoon ideally as feet tend to swell a bit throughout the day.
In our local fb groups, it seems everyone swears by Altra and Topo for light hiking. They look like duck feet to me, so that's a no for me, but maybe yes for you.
It's March and at least here daylight is starting to last longer than 6 hours again so I'm going on a hiking trip this weekend. Nothing particular interesting so I'm going to ask a question to get this thread out of hibernation: Anyone got unusual hiking food preferences? I've baked an onion tart that I'll be munching on during the day