Advice on builds for (F) Robin.

She's a pretty good unit. Nice counter to Brave Lyn who you see EVERYWHERE.

I generally agree with your build. Her speed is not that great. I see you're trying to get desperation/brash assault combo going, and using Ardent sacrifice to get within range.

Another option is a "breaker" skill in B slot. Then you can free up your assist for something movement based, which I find more useful.

Unfortunately, F!Robin is a very outdated character with mediocre stats and unimpressive skillset for today's standards, which is made more unfortunate due to the inability of tuning her IVs & limited merge potential.

The best bet to attempt making her viable would be a standard raven tome set like this since that at least maximises her advantageous matchups. Even then she is still outclassed by Boey in this role.

Weapon: Gronnraven+
Skill: Reposition or up to preference
Special: Moonbow/Glimmer/Bonfire
A: Triangle Adept 3
B: Quick Riposte 2/3 or Bowbreaker 3 or B Tomebreaker 3 or Axebreaker 3
C: Flexible
Seal: Distant Def 3

1. Ardent Sacrifice isn't worth it on your build because she needs to use it at least twice to get into BA/Desperation range.
2.The problem with this setup is that QR saves you from investing both B skill + seal and provide much more consistent results. Robin's base atk is absolute garbage so QR or breaker is almost mandatory to effectively kill
3. Ignis is not optimal on Robin because she doesn't have any innate cooldown reducing skills/weapons so she will have difficulty procing it consistently, 32 DEF is not bad but still lackluster to OHKO units (which is the main reason why people take Ignis/Glacies in the first place)
4. Wolf tomes are too niche to be used reliably unless you really hate Rein or B!Lyn... who are better countered with raven + TA set-up in the first place. Unfortunately, you will often still fail to kill most red cavalries in the first place due to her poor base atk.

Here’s mine. She is super amazing against Rein and B!Lyn with the distant defense build, and gronnraven+. I think better than with the Gronnwolf+ tome (because I had that on her and refined, and she was not holding up against B!Lyn at all).

Can deal with reinhardt lyn and cecilia without being healed needs an attack spur/drive sometimes

I personally went with her default kit but changed her A-skill for Fury 3 and put on Reposition. C skill is flexible but good choices are Threaten Res or if you like to double as support, hone atk/spd or drive spd from a 4* Tailtiu.

I like to keep her B Tomebreaker because she's the only one that has it. Unmerged, she can even destroy a +10 best build Reinhardt on counterattack if she has Deflect Magic 3.