I was appalled to learn from this thread that the other party’s testimony is not even considered or requested.
That’s not what was said. If the other party cannot be contacted or has no wish to participate, the petition will still be heard. But a true attempt to contact the respondent will be made.
Even after the decree is granted, the respondent can appeal it to the ROTA and it can be reversed. That has happened in a very public way in recent years when the decree of nullity was revoked in the case of Joseph Kennedy.
What happens to the other spouse if he or she loved their spouse and didn’t want a divorce/anullment? Do they not get any voice in the matter at all?
They are invited to respond and give their side of the story and provide their own witnesses.
Must an anullment FOLLOW a secular court divorce or is is SUBORDINATE to the secular courts (which seems profoundly ironic to put priority on secular courts before God).
In most cases a divorce must already have been granted. That shows that the marriage has truly broken down.
Does the OTHER spouse still retain an orphaned “married in the eyes of the church” status and have to go back and refile their own petition so they can get their own anullment and be free to marry again in the church?
Of course not, if the marriage was invalid it was invalid. The decree is sent to both parties if the respondent’s location is known.
Are they left in “Limbo” when the petitioning spouse prevails and receives an anullment or does the Church issue TWO declarations of annulments - one for each spouse?
There is ONE decree of which many copies are made since copies of the decree are sent to the two parties, to the baptismal parish of both parties as well as to the marrying parish if they didn’t get married where one of them was baptized.
The I can just see it now - a person who actually did not want a divorce suddenly receives a letter in the mail that says “congratulations we just declared your marriage invalid before God and your kids appreciate you for your donation of DNA - good luck”.

Do the children get no voice in the church essentially declaring them bastards by fiat - even if they loved the parent declared invalid by fiat?
The children are not ‘essentially declared bastard by fiat’. Any child born of a putative marriage, IOW, one that was presumed valid, are legitimate.
I have never had to deal with this circumstance but from an objective fairness perspective I AM NOT COMFORTABLE with the whole anullment game and think its for all but about 5% of the cases just a way to get out of one’s obligations and start over with a second chance (like confession almost). The whole entire concept of anullment is troubling to me since it seems to mean literally that the marriage was “invalid in fact” before God even before the ruling of nullity. How many Catholic couples are living as married couples HAPPILY but in fact are invalid due to an error in form or intention etc. but they are otherwise content?
Probably many: those who spoke their vows with no intention of having children, those who married without intending to be faithful and those who married thinking 'Well, if it doesn’t work out I’ll just get a divorce.
Where is the symmetry in all this? Why are we not asked to have marriage maintenance reviews from time to time to REQUIRE all married Catholics to VOLUNTARILY submit to a declaration of “VALIDITY” AFTER people are married every few years to prove “just in case” that the marriage is valid. Why is the court set up on a one-sided “hearsay” sort of justice and in a retrospective reactionary sort of way rather than peremptory BEFORE THE MARRIAGE IS EVEN GRANTED IN THE FIRST PLACE???
The Church does attempt to ensure the validity of each marriage before it occurs by asking the various questions of the spouses that ensure validity. But how many people do you know are going to sit at the pre-nuptial interview and reply “No” to the questions about having children, being faithful and marriage being for life when they know that a negative answer will mean ‘no marriage ceremony for you’?
I am NOT comfortable with the entire anullment system and think it needs to be rethought out.
James