I got to the "Extremely Dedicated" questline with the last Infusion Shard and upgraded to 5.2.
Well the thing locks up when I open the HQM Book and try to complete the quest. I was able to click spam the "Unclaimed Quest" and then I got in to claim the reward, but as soon as I exit that section back to the top where the other seeds are it crawls. I created Certus seeds and was also able to click spam the reward claim. I then went and created Fireprotection seeds, Ghastly seeds, Withering seeds and now I can't even click spam to open the sections.
It seems you have some sort of bad infinite loop going on. CPU is not really that bad, but mouse input is broken.
EDIT:
I was able to get it to work in an odd way. I force quit the client, then spawned in an edit book. I am not sure if it was needed because I didn't use it to reset the quests. I spam clicked the unclaimed fireprotection seeds and it was still locked. So I tried clicking an old completed quest and that worked.
Then I went back and tried the fireprotection seed and nothing, but right after I clicked the completed "what doesnt kill you" shard quest and it opened the fireprotection seed quest and I was able to claim the reward for them. I then repeated for the slimy, ghastly, and withering seeds and that worked too. It still slow, but it is a workaround for not being able to click.