I too would love to see a good picture of each plant. That certainly would help in diagnosis. Generally however, the first things that come to mind are 1) that brown patch on the shimpaku could be the result of an un-noticed break of the brown branch close to the branch that it is joined to. It's not on common to have that kind of thing go un-noticed when your working on them, only to have them brown out and die in a week or two which would be quite normal for a juniper. 2) I'm more concerned about the yellowing of the Rocky Mountain. My first inclination would be to ferterlize just like you did, but with a more substantial and quick acting fertilizer like general purpose Miracle-grow. Organic cakes are good but they are slow acting. If you did not do anything with the root's in the workshop I would not suspect it's anything significant at least yet. Most junipers are slow in showing stress. A picture would help a great deal.
Boaz, Kentucky US growing zone 6A