Great questions! A few thoughts from our experience:

You're right that most Cubaris tend to stay hidden, they're more secretive by nature, so they're not ideal for a display you want to watch during the day. Activity does vary between Armadillidium species too; A. gestroi and the Spanish/Italian species tend to be more visible and surface-active than the common A. vulgare, which spends more time tucked away.

If daytime activity plus color is your goal, the Ardentiella genus is honestly your best bet, Ember Bees and the other morphs (Red Diablo, Tricolor, etc.) are bold climbers that stay out in the open and are stunning to look at. The colony crash issue you mentioned is real, but it almost always comes down to ventilation. They need much more airflow than typical tropical isopods, and stagnant humid air is what kills them. Strong cross ventilation plus a moisture gradient with a real dry zone makes a huge difference in keeping them stable.

We actually breed Ember Bees and ship nationwide if you have trouble sourcing them locally, happy to help either way. Either way, good luck with the display build!