I didn't encounter any bugs that annoyed me enough to remember. The achievement your talking about did happen to me where I romanced Liara in the ME1 and later Garrus in ME2 and ME3, but didn't get the achievements for it. That has since been fixed and I was able to get them this time.

A graphical glitch I encountered was in ME2, where the side of the screen had a green bar, but that's also been fixed.

Again no bugs bothered me enough to remember or the two I just mentioned have already been fixed.

^you got the Paramour achievement in ME3 because Liara’s tagged as a Paramour. There is no such tag for her in ME2 because, as I said, she was DLC in the original.

That’s what annoys me, BioWare spent time and money to update and upgrade all three games, they had to write new code but couldn’t just put in a little code for those of us who romanced Liara in all 3?

That just reminded me of the eye ball bugs.. my Shepard would always do a Undertaker eyeball look in every cutscene for a couple of seconds.

I think this is a case of it not being a priority or even a big deal to start with. I think everyone kind of accepts that she doesn't grant you the achievement and it makes sense why.

As I said, it was not a bug till now, so it's not odd that the dev team gave no consideration

She spent ages looking for your body, fought Shadow Broker agents, Collectors and betrayal multiple times and then gave your body to Cerberus and waited 2yrs for any word about you, just to have a dlc that lets you rekindle your love but not get a achievement. Then wait till the masses want Remastered/Legendary edition and still not achievement.

Sloppy work from BioWare

Not sloppy work. As you said, Liara was DLC, so of course, the achievement wasn't going to count her then. It's standard practice not to tie expansion work with vanilla achievements. And as for LE, it wasn't a big deal for anyone till LE came out. Now since Bioware is making patches, they might get around to making Liara in ME2 count as long as fan interest is made known throughout Bioware sites

Sloppy work? She's not one of the main romances in Mass Effect 2, unless you romanced her in ME1 you can't romance her in the DLC. So it can't count towards the achievement as she's not a squadmate and she's not there to do the business before Suicide Mission. This isn't a bug as it wasn't even meant to unlock anyways, it's a mild inconvenience at best.

Honestly, I'm more interested in them hopefully fixing some of the current bugs like with Aralakh Company and Annual Xen not showing up in the war assets