You might want to go to Hobby Search and look up what Tamiya recommends for their own German aircraft models.

The only paint I see which has RLM in the title is XF-22 RLM Grey.

I love Tamiya paints, especially thinned with Mr Levelling Thinner, but yes the range is limited compared to some other manufacturers. I end up mixing my own colours and not worrying too much about an exact match with factory swatches. Here's why...

Colour is dynamic - it changes. Operational wear and tear combined with weathering and variations in the quality of paint, together with the effect of scale on perceptions of colour, and prevailing light conditions mean that an 'exact match' is more often about art than science for me. If it looks right it is right that's my motto. Colour references help if you can find them and also serve to show how colours aren't static.

If mixing seems daunting then have a go before you apply paint to your model, and check out some of the artist's stuff on Youtube to get a glimpse into colour theory. Once you start you'll feel liberated from the tyranny of the search for the perfect match. Ahem, getting carried away, but you get my approach by now. Not everyone likes it, but it works for me. Mixing colours has become part of the fun :-) Oh, and I have fewer jars of partly used paint slowly drying out too.