I understand that this event ends very soon, however I’ve still decided to post this as a bug-report just in-case this could still be resolved.
It seems that the items in the last row of the codex (specifically the items which require keys) are not always clickable while on mobile. This makes it very difficult (or potentially not currently possible) to claim the cursed variants of these items if your only available device is a mobile device. Switching to a desktop device allowed me to select the item and successfully claim the ‘cursed’ form.
There are unfortunately also a few other smaller bugs which I encountered in the Halloween Spotlight hub. Luckily, none of these other bugs block users from completing the event. If the team would like a list of these of these other bugs, please let me know! I’m just not too sure if creating a bug-report would be ideal for these, given they don’t impact completion and the event is near-end.