Yes. But it's a bit hazy still.
We have this from Peter:
Aiki wa wa to toitsu ni musunde iku no de aru. Ume to matsu no shikumi de aru shochikubai no oshie.
Aiki is peace and harmony, the pine and plum together, the teaching of sho chiku bai.
Let's skip the first sentence for just a moment and look at that second one. Did anyone else notice that there's something just not right in there (he mentions pine and plum together but not pine)? If I might try a stab at it, I come up with something along the lines of:
The workings of shochikubai (pine, plum, and bamboo) can be found in the pine and plum together.
Ueshiba stating that a common Japanese term, "shochikubai" (as Peter noted, it has google hits of 774,000) can be discovered in his aiki training by looking at the pine and plum together.
What does he mean by pine and plum?
We go back to Peter's TIE article:
錬り清めゆく(neri kiyome yuku)
気の仕組 (ki no shikumi)
いつここ/ いずこに生るや (itsukoko / izuko ni naruya)
身変るの水火 (mikawaru no iki)
(The Japanese text of Abe differs from that of Stevens in the fourth line.)
The pine, the bamboo, and the plumThe make up of Ki that we are training to purifyFrom where do they arise?The Water and Fire of the change in the self.
Here Ueshiba notes that shochikubai arise from Water and Fire and the change in self.
We know from your translations that fire and water are placeholders for in/yo training. So, if we substitute, we find that the pine and plum are in and yo while the bamboo must be the change between them.
In other words, Ueshiba's saying that his view of shochikubai is that, in aiki, where one must have contradictory spiraling forces, the pine and plum are the contradictory forces while the bamboo is the area in between where the change occurs. Even more so when the contradictory forces are reversed.
Does that make sense?
Going a bit further in Peter's article, if we take the pine as irimi and the plum with void, we see that in contradictory forces, we have active/passive here. Then we see bamboo as tenkan, or change. Given that we are dealing with spirals and the area between contradictory ones, tenkan is probably a natural occurance.