Well the Heart Sutra is an important Sutra in East Asian Buddhism, too. Though the Heart Sutra is more philosophical in content, I'd say, that it is the single most recited text in East Asian Buddhism. But it's great, that more devotional texts like the Amida kyō are also being recited. The website of the TBI states, that practitioners tend have problems with devotional practices - is this the reason the focus for lay Buddhists (outside the TBI) lies more on "philosophical" texts rather than devotional texts like Kannon gyō, Enmei Jikku Kannon gyō or the nenbutsu? Or is the list of texts in the daily service not complete?
I would say, that many Western Buddhists are in fact unfamiliar with the more devotional side of Buddhism and mostly focus on the philosophical and meditational side of Buddhism instead. Maybe that is the reason for high fluctuation in lay Buddhist groups, because the emotional side seems to be less developed (but that's just a wild guess you are free to ignore
I've searched for these texts in the internet and many are available, though not in this compilation. I have collected all texts I could find in transliteration (and translation) and checked with my copy of the Tendai service book, though I'm not finished yet. If you are interested I can send you a pn with the texts in transliteration (and translation - and Kanji, if you like).