Re temporal use:
(i) Exx (5) and (7) show no _hag_, indicating the correctness of a relative rather than a coordinate analysis, unlike for English _Sir Pitt has been and proposed for to marry Miss Sharp_ (= _Sir Pitt proposed to marry Miss Sharp_, plus surprise) (Oxford English Dictionary, s.v. _be_). Interestingly, no example with _ma_ occurs, which alternates with _e_, _hag e_ in the case of overt temporal heads.
(ii) Gourmelon gives dialectal indications for his ex, these should be kept, because it allows comparing rannigs and usage of _hag_ with overt temporal heads (e.g. in Urien's investigation of these matters for Leon).
(iii) Gourmelon's local French ex is also interesting.
(iv) A different term might be useful, because reduced relative clause is ordinarily used for nonfinite relatives. Cf. Keith & Brown, _Dictionnary of linguistics_, 2014:
REDUCED RELATIVE CLAUSE A relative clause in which the relative pronoun or subordinating conjunction has been omitted, along with some form of be. E.g. _The guy who was repairing the leak has gone reduces_ to _The guy repairing the leak has gone_.
A "headless relative" might be useful, although it is not ideal either, as it standardly refers chiefly to free relatives.
(v) Theoretically it may be worth highlighting that this is, as far as can be told from the descriptions, a "construction" in the sense of Construction Grammar: _bet_ seems necessary, e.g. no _Me a vo hag ez in da gerc'hat amann da Rosmeur_.