Ok let's work through your post and see how it stands. You state:
sure, there is an example from Philemon 15, where Paul writes, "For perhaps he therefore departed for a season, that you should receive him forever", where αἰώνιος can hardly mean "eternally, without end", but "during their lifetime". Here it is used in a limited sense.
And I agree that there are some that place "quality" as the consideration of the word. However, the "eternal, without end" definition fits perfectly, and more precisely with the balance of the use in the Scriptures.
When Philemon returned as a brother, and not as a slave, it was not a temporary relationship that Philemon would enjoy, but that estate established by the Lord for eternity. All believers are adopted as sons of God and eternally so without beginning or end.
Philemon and his former owner were united forever as relatives, and not as owner/slave.
So, although your example is precious, and can be seen in the light you presented, it can also be shown that it fits more perfectly into the eternal without end definition.
When the writers of both Testaments wrote in Hebrew and Greek, they did not invent the languages, nor change the uses or meanings of them, but used them as they are. Like the noun θεός , it is used for the One True God of the Bible, but also for humans and even the devil! Christians must not be found to change the meaning of words to suite themselves, lest the be charged of change for their theological purposes, and therefore cannot prove their beliefs by honest means. I believe that all that the Bible teaches to be true, and can be understood and defended against any charges of dishonesty or tampering or twisting.
Let me give you this about accountability in which I humble myself and submit.
Truly, I often and I regularly post on the BB. Typically when working in the ancient languages, I openly call for others, on the BB who remain intellectually sound and are well schooled in the languages to review what I have written and make any correction to what I render.
Truly, it is a great honor to have them take the time and I trust that when the time comes that my work becomes questionable, they will gently prod me to understand that I no longer participate in discussions in which the languages are a matter of importance. These are long BB friends who I hold in highest esteem and am honored that they regard me in such a manner as to be worthy of inspection and correction.
Considering the intellectual frailty that I push against every moment it is foolish not to rely upon those good and kind people to be as a guard so that I never post the Scriptures with a rendering of error.
In previous posts, you have accused me of twisting the Scriptures. It was shown not to be true.
Here you seem to imply the same. Again, it is shown not to be true.
What is seeming to be uncovered is were you might render what is more liberal and I take the more conservative used meanings.
For example, you use θεός as if what you present is disagreeable.
It is not, for like most words, the definition is determined not by a dictionary, but by contextual usage.
Just as in the Philemon 15 verse, you took what was the earthy temporal and I took that estate of the celestial eternal.
You selected one definition and I selected another when it came to aiónios.
I viewed the context showing the estate of adopted into the family that had no beginning nor never ends.
Perhaps when you find another place in which you can ascribe the earthy termination, you might reconsider just how more perfectly the word fits in the eternal.
Ultimately, to take the use as temporary, even if highlighting the quality, it would (imo) weaken the actual message given, that eternal is not just no beginning, no ending, but of the highest estate possible when associated with plan, life, purpose, judgment, ...