Hi Ron,
perhaps someone else can improve upon this, but here's a firt shot at German.
german_date ::= any_year
| german_r_month dot any_year
| day dot german_r_month dot any_year
| german_r_month any_year
dot ~ '.'
any_year ::= year | year_bc
year_bc ::= year german_bc
year ::= number
german_bc ~ 'vc'
| 'v.c.'
| 'v.chr.'
| 'vchr'
| 'vuz'
| 'v.u.z.'
day ~ digit
| digit digit
digit ~ [0-9]
german_r_month ~ 'jan' | 'feb' | 'mär' | 'maer' | 'mrz' | 'apr' | 'mai'
| 'jun' | 'jul' | 'aug' | 'sep' | 'sept' | 'okt'
| 'nov' | 'dez'
