Menatlly and physically amused - this is a new concept to me for a Hermann's Tortoise. I imagine it is possible that tortoises may find something amusing, but I rather tend to doubt it. If you mean, on the other hand, is this enough to keep the tortoise mentally and physically stimilated - my guess would be yes. I have to guess as to the mental aspect since I cannot get into the mind of a tortoise.
I currently am keeping two Hermann's Tortoise babies. They are doing fine in a large enough tank with a substrate of Afalfa and Timothy Hays, a water bowl, a food bowl, and a piece of artificial bark, shaped in an arch, under which they can hide (they also hide under the hay quite regularly). In the warmer months they will be outside, and whe adults they will be outside year round aloowed to hibernate in winter. They seem to be doing fabulously. Their appetities are great, they drink regularly, they bask regularly under both UV and heat lamps, they utilize both the warmer and cooler end of the enclosure (so I know the thermal gradient is good), and they are growing slowly but steadily with absolutely no pyramiding of their shells.
As for branches I do not supply any, I would be concerened they may attempt to climb them and fall over upside down (rather stressful if under the heat lamp). Nor do I supply any artificial leaves as I would be concerened they may try to eat them, and may actually ingest some part of them. Are you sure your fake leaves are nontoxic to tortoises?
On the topic of foods, what are you feeding to yours? I am interested to hear what types of food keepers on the other side of the pond are feeding to their animals. I feed mine a wide variety of greens such as: green leaf lettuce, red leaf lettuce, escarole, Romaine lettuce, collard greens, spinach, carrot greens, kale, dandelion greens, grass from my lawn (the lawn is untreated - no chemicals), and some other greens from my yard. I also feed them other vegetable matter such as: green beans, brocolli, brussel sprouts, cabbage, alfalfa sprouts, radish sprouts, grated carrot, red bell peppers, tomatoes, sweet potato (the type with the orange inside), dandelion flowers, petunias (flowers and leaves), and geraniums (red flowers only) among others. I usually avoid all animal protein except for a now and then feeding (maybe twice a month) when I will feed them something of an animal protein base such as a superworm, a wax worm or other grub type insect larva or an earthworm. I supplement their diets with some powdered calcium now and then, and with some powdered vitamins also.
Good luck with your Hermann's Tort.
Best regards,
Glenn B