Great update! I'm happy to hear that you've been able to drop the temperature of your tank!
On the topic of enrichment and mental stimulation: (this can be a tricky subject, and many people have their own opinions on the matter, if anyone disagrees with anything I say I would be more than happy to chat about it. I think there can be a lot of misconceptions about octopus intelligence and enrichment needs, and I believe open discourse is very important) -- I think that your octopus probably does not need any sort of additional mental stimulation (toys, puzzles, etc.). The main reason is simply that these animals would never experience these types of stimulation in the wild. There are no rubix cubes in the ocean, and there aren't any legos or jars filled with crabs either. People love to give things to octos, watch them struggle with it, and say "wow look at it play with the toy!" which I think is a gross anthropomorphisation of their prey-manipulation behavior.
Octopuses are prey-driven animals, and they are foragers, which means that they have a natural tendency to explore their environment, as well as any new things that are added to the environment. This means that of course they will grab and manipulate most things that are put into their tank. Does this mean that the animal is playing? Or is it just exploring a novel item to find out if its edible?
We don't know if octopuses get "bored" in the sense that humans do, but to prescribe boredom on an animal and give it random toys to play with is a very human-centric way of thinking (eg: if I were in the octopuses situation, I would be bored. Therefore, the octopus must also be bored, so I should give it a toy)
I think the most "natural" way to provide enrichment to your animal is to diversify the food that you give it, rather than give it frustrating challenges that it doesn't understand (eg: crab in a jar).
In addition to varying your feeds, you can also change up the aquascaping in the tank every few months to give the animal a new environment to explore. Alternatively, you could try to hide crabs in new spots in the tank to give the animal something to hunt for.
Either way, octopus enrichment is a much-contested topic. I am in the camp of people who think they probably don't need any sort of puzzles or toys because they would never experience these things in the wild, but I am very open to discussion and happy to hear the opinions of others.