Of course pH goes up like that. But you're entirely missing the point.

Right from day one when Agfa began making Rodinal (until the major shift in 1964) the important part of manufacture of it or the substitutes was that there was just enough Hydroxide to convert the metabisulphite into Sulphite and react with the p-Aminophenol. See the 1910 "Agfa" Book & remember who wrote Agfa's German handbooks - Dr Momme Andresen, who discovered p-Aminophol and designed Rodinal. To quote "Agfa-Rodinal contains only an alkaline salt of Paramidophenol, but no excess of caustic alkali". Later when they manufactured with Potassium Sulphite the level of Hydroxide dropped substantially as would be expected due to the reactions taking place.

Whether there's a trace of excess Hydroxide in Calbe R09 or not is immaterial what's important is that the bulk of the hydroxide has reacted to form that "alkaline salt of p-Aminophenol, that itself will increase the pH.

What's certain is that the pH is significantly lower than it should be from the amount of Hydroxide in the formula.

Ian