On 15 Aug 2014, at 18:37, riki wrote:

Please find herewith my custom theme. […]

I do not see any issue here.

I saved your theme and switched to it. Then changed langauge to Fortran — Modern and entered ‘recursive’. This keyword is shown in bold and with a slight color change (rather subtle though).

The rule in my Fortran grammar does btw not include as many keywords as yours. Did you edit the grammar? Did you verify that you get the storage scope (using ⌃⇧P)?