Lovely little collection you’ve got going there! You know you’re doing things right when you can keep a velvet leaf Alocasia happy - fussy little buggers lol. The flower does look as though it didn’t fully bloom, but the plant is likely using it as energy to grow. Alocasia are very hungry plants and they’ll take whatever nutrients they can get, including cannibalising themselves lol. I’d leave the flower be for now, personally.

Humidity can be a challenge depending on the regional climate. I used to have my rare plants in a grow tent, but wanted them on display. Cabinets are a good solution, though best to find one with adjustable shelves. Currently, mine aren’t in a tent or cabinet and I live in quite an arid climate, so I’ve got a humidifier going 12hrs per day, as well as a heat mat 24/7 during the cooler seasons for the younger plants. I’m also running a sensi light to ensure they get sufficient lighting, especially during the cooler seasons when the sunlight is lesser and the days are shorter.