finish the jobs Rolan started?

[Dweller Beyond the Threshold]

I'm at this point in the game. The mission marker says 2/8 completed, but now I did a bunch of those missions with the orange 2 crossed swords icons next to them, but it is still at 2/8.

Also, when can I unlock the character-specific sigils? I want to get the one that makes Zeta's air-loop's timing easier.

[Tanya]

Only gives you progress once you get an entry for the diary, there are 8 in total, not gettin progress for every mission you complete is intended, just keep doin the missions they tell you to do till you get all 8.

As for the character specific sigils you can buy them from Siero or you can use the tier 4 transmute to get them.

[Suzaku]

Just complete all new quests. That quest is the entire chain of quests that leads to proud difficulty.

Character-specific sigils unlock at Siero. I think a popup even tells you when they become available.

[Aphelium]

Keep doing the orange quests and they will give you some books, not all quests give it to you. You keep unlocking new quests that do, however.
The sigils start appearing when you unlock the transmarvel, I believe some of them appear before that and are buyable at sierokarte at the trade option and the gold medal exchange.

[Tiasmoon]

You can also get +version's of the character-specific sigils from transmarvel. (becomes available when you access to Level 3 transmutation)

Both regular versions can be bought from them. One with materials, the other with Dahlia coins.

[Emilia Tempest]

The character specific siglis you unlock after you completed the after-story chapter (aka the one you are currently in).
Focus on the quest that have a marker on them (its on the left on the quest bar).
You only get progress for "finishing what roland started" if you get a note entry which was pretty confusing tbh. when I played as I thought my game was bugged since when I did a mission with a marker on it I never got progress.
also you dont need to finish every mission you get access to, the ones that dont have a marker can be ignored if you are only after the progression.

Shiro sells two types of character specific siglis, ones you can get by exchanging materials and the 2nd you get from golden dahlia badges (aka using "Quick Quest" with an Open lobby).
Yes they are two DIFFERENT siglis with different effects.
You can get gold dahlia badges by doing quick quests as a closed party but the drop chance for that seems to be stupidly low