The HLC says that you must change all critical hits to normal hits. If you focused for your action and you rolled two criticals, a normal hit and an focus symbol on the attack with the HLC, then you change all your hits to normal hits due to HLC text, could you spend a focus to change one hit to a critical hit?

The way it works per the FAQ.

Roll your dice and change any [crits] rolled into [hits]. After that anything that changes a [hit] to [crit] or if you roll the die again and it comes up a [crit] it stays a [crit].

However, you can't use a Focus to turn a [hit] into a [crit] ever. Focus doesn't work that way, the only thing it can do is turn any and all [eye]s into a [hit]s.

Yeah, focus cannot change a [hit] to a [crit]. You could reroll some dice with target lock and keep any [crit] results you get from that though.

If you happen to be using Marksmanship instead of Focus that WOULD turn the first [eye] into a [crit] before turning the rest into hits.

I just have to double check, if I have HLC and roll 2 hits, crit, and focus. I turn my crit into a hit but if I used Marksman action my focus will still become a Crit and does not need to be changed into a hit?

I just have to double check, if I have HLC and roll 2 hits, crit, and focus. I turn my crit into a hit but if I used Marksman action my focus will still become a Crit and does not need to be changed into a hit?

Correct.