There is new API (added to AT-SPI2 2.52) which provides a means for ATs to obtain, set, and clear text selections which span multiple elements. See https://gitlab.gnome.org/GNOME/at-spi2-core/-/blob/main/atspi/atspi-document.c?ref_type=heads#L176-307 Orca's generic web support will be using that new API soon. When Orca starts using that support for WebKitGtk content, it would be great if this API worked in Epiphany, et al.
<rdar://problem/122622017>