The points are well made.
The OP has explained how he previously received a FP followed by denial of RC due to lack of supporting evidence; (presumably in slightly more favourable conditions).
This time the logistics and timeline seem more challenging. The status of the spouse is indeterminate.
My concern is the over 6 months absence (not justifiable in terms of strengthening life within EU ie
qualitative elements relating to the level of integration) breaks a continuity of residence.
That suggests past residences/timings are reset rather than carried over to be used to apply for ROR in coming months (even if residence in UK is reestablished).
And absence over 2 years would end even PR so its surprising to hear past residence/timings may be utilised in the future.
It seems at odds with free movement that an estranged spouse living for years outside EU appears to have more access back into EU than, for example, a settled EU citizen who goes abroad (and in the same period of time, or less, would lose their PR).
As per Article 13 of the Citizen's Directive, the Community legislature saw only a specified number of circumstances as giving rise to a retained right of residence. Recital 15 states that family members “should be legally safeguarded in the event of the death of the Union citizen, divorce, annulment of marriage or termination of a registered partnership".
It is only in respect of “such circumstances” that measures should be taken to ensure family members already residing in the territory of the host Member State retain their right of residence exclusively on a person basis.
https://tribunalsdecisions.service.gov.uk/utiac/37677
If the one year in UK for ROR is indeed regardless of absences from UK
over any length of intervening time then that can only help OP.
In addition, if legal measures may be taken to stay the divorce or for access/custody then all well and good; divorce proceedings are unknown territory to me.
That's a glimmer of hope in a difficult scenario.
And I have already suggested how s.40
UK Borders Act may be utilised to help determine the estranged spouse's current status.