Colour balance is the thing that tends to change over time with a film, so I wouldn't necessarily be too surprised. I've never used out-dated Reala, so I couldn't say for sure exactly what to expect. Of course, if you're looking at prints it could be the printing that is at fault rather than the film. Though I would have thought that Peak could be relied upon for decent QC.

In general my experience of Reala (quite a long time ago now admittedly) is that some colours can be very punchy (reds and greens as I recall) but that flesh tones are quite well-controlled, making it a reasonable potrait film. However, it doesn't have the more subdued contrast of a film like Fuji NPS. It is much finer grained though, so perhaps a better choice for 35mm rather than MF.

One other thing - old leaf shutters can be slow, as I'm sure you know - are the negs unusually dense? A bit of unintended over-exposure could perhaps be the culprit.