there is actually a way around these 2 not unlocking.
For the paramour achievements/trophy they can be cheesed by loading up any save in ME1, then saving over that save, then exit to main menu. Then press start on ME2, and trigger the booty call scene. Achievement pops. If you repeat it again, you will get the paramour 3, though it is a glitch, that should only be patched after the achievement is confirmed to be unlockable as it is intended.
For insanity 2 and 3 there is a glitch that if you reload the autosave at the beginning of the saren fight, you can earn the insanity 2 and 3 achievements just by killing him again on insanity. Personally i am still going to play on insanity anyway for the consistency and i've played OG ME3 so many times on insanity im used to the difficulty.
However, it will not trigger the Long Service Medal achievement, and some people are mentioning on reddit that this achievement doesnt pop correctly for some people either.
Also, I don't know if it is related, but on the extras menu for all 3 games where it shows the achievements in game on the menus that show them, it doesnt show these achievements highlighted even though they have been earned.