Can see photo now (magic of technology apparently - now you see it, now you don't). Have you tried feeding it with an appropriate slow release fertiliser + something more immediate like organic lifter? Watered in thoroughly of course. Good luck. Worse comes to worst you can always replace it.

having inherited a run down garden with several mature Japanese Maples we've begun the resurrection by making an island out of one tree in a raised garden bed surrounded by recycled clivia (there are many other hardy strappy plants)...i wonder if the client understood that they will be forever having to cover their Yucca's before expected frosts they may be more open to alternatives and maybe they mean a plant with architectural shape, like a Yucca eg Phormium or Grass trees or Cordylines etc in a feature bed or big pot...the first picture is my own rescued Japanese Maple and the second is my inspiration from HOUZZ

Not being in Australia I do not know what Wallaby's eat but I think in New Zealand the native flaxes are safe from the Possums. I think you need local knowledge and a plant nursery - the people that grow the plants (e.g. a plant wholesaler) might be able to give you the best advice and a discount for a bulk purchase. Good Luck.

hi Katie, my experience with my plant-beds next to the pool, (at back of pool=1 metre deep x 3 metres long) & along side of pool =50cm deep * 15m long) - .. initially I planted Palms - removed them after 15 years.. .. I re-planted the 'back-bed' with 'Birds of Paradise, large' - I removed them last year, after 10 years, bcoz they grow very big and spread in all directions & broke-up the garden-wall. Over the past few months, I have been replanting all of my garden , still in-progress- . in the beds near the pool, I have planted - ...…. Tiger Grass bcoz it is not as vigorous as Bamboo, doesn't grow as tall and is in small clumps ….. interspersed with some 'ball-shape plants'.. (for example,EUPHORBIA Ascot Rainbow, RUBY Leaf Alternanthera Dentata Compact) and some silvers - check your local nursery for small tidy, compact shrubs....or, small grasses for a different shape Make sure that whatever you plant does not have any noxious sap etc.. .. https://www.childrens.health.qld.gov.au/poisonous-plant-philodendron/ whatever you plant, there will be some drops into the pool - just make sure you turn on your vaccuum at least once a week...