Real issue was that transform manipulators' code was calling TRANSFORM_OT_trackball with data (PointerRNA) from VIEW3D_OT_manipulator. That op has constraints props, while trackball has not. This created some kind of "ghost" properties, that showed up in redo panel.
Why this only segfaults in BLF_pgettext in 32bit builds remains a deep mystery (currently dusting out my 32 vbox to try to understand it...). BLF_pgettext is supposed to be pretty secure. :/
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