Moisture movement through Bildrite and WRB – GreenBuildingAdvisor

1987 MN home, zone 6a. Wall assembly is drywall, interior poly, 2×6, insulation batts, bildrite asphalt board, and masonite. WRB selection worries me due to due to wall’s inability to dry inward. I am suspicious of how effective moisture transport can be at a flat and tight interface between asphalt board and plastic wrb. Might tar paper perform better since it can wick liquid water out of the bildrite and evaporate from there? Also, any liquid phase water at the bildrite-hydrophobic tyvek interface might be harder on the sheathing than at a hygroscopic tar paper-bildrite interface.

Please poke holes in my reasoning. I understand that adding a wrb should help with bulk water. However, the remaining balance of moisture from any source might have a harder time escaping with the addition of a new layer. The wall appears to be solid up to this point with the exception  of where building practices or errors (missing kickout, siding touching roof or close to ground). But I am comfortable needing those repairs after nearly 40 years especially since the source of that water is addressible. Perhaps the breathability of the bildrite has been the wall’s saving grace and I am about to throttle that. 

I understand that using plastic wrb is super common, but my fear is that the practice is born out of price/construct ability and that houses of my era getting remodeled are going to have major, slow to develop moisture problems in 10ish years. Sorry for the extremely long post, but wanted to lay out exactly what I am thinking. Would greatly appreciate any advice, correction on the building science, or even just reassurance that I am way overthinking this.