I've been looking at this stuff longer than I should lol but the conclusions that I've come to are that the welder handle looks like a droid caller to me. Maybe they had a spare prop and put it to use. And after looking around I found an article on Wookiepedia saying the masks in the ESB scenes are called roamer 6's and the picture shown there is what Hot Toys has based Leia's mask off of. And looking at the image of Finn with the gas mask that echo posted, it appears that he has a cannister similar to how it looked in ESB. So presumably someone pointed Hot Toys to this
https://starwars.wikia.com/wiki/Roamer-6_breath_mask and that is what they went with. To the point that jme_c made, I'm still super excited for this figure and I think she looks fantastic but again I would love to see this stuff get as close to movie accurate as possible and its a bit of a shame that some fans on a forum can point out the inconsistencies in some of these accessories but the design and art department at Hot Toys doesn't seem to notice them.