Blas and Other Battery Experts-Help!

[ERA Chas]

Strange (to me) battery problem in my DD. Well maintained, low miles, garage kept, no mechanical flaws.
Battery is a Bosch, top line, less than 3 year, old series 25.
The problem is battery fluid drawn out of the cap vents, seeping down the case and rusting the well it sits in.
I puled it, neutralized the acid in the well, coated with rust converter and cleaned the battery. Thinking the level too high, I wicked out fluid just to the level of the split rings. Cleaned every thing and reinstalled.
Battery tested 12.5 - 12.6 in 30F and 60F weather. With engine on, reads 14.2 - 14.4 under same conditions and at 1200 and 2000 RPM fast idles.
I've done this three times and continue to see fluid at the caps and muck in the well. But the fluid level is not down to the plates.
So I think the charging system is OK but can't figure the battery. Am I boiling fluid? It is just being wicked out by the vent cap design? And yes, the batt is firmly attached in its well.
Appreciate any advice.