The item should probably be called "first aid kit" in english as well, seeing as that's what the description says it is. I'll change it to that.
I think the other "First Aid" string (with capitals) is for the text when you use the first aid kit in-game, and it gives you the option of what limb to heal. Actually that should just use the name from the .json. So yeah, that needs to be fixed too.
I'm aiming to fix most of the ambiguous strings for 0.9, so the more bug reports the better.
And bad english is fine, i can understand ;).