A trademark registration does indeed protect a mark only in the courtly where it is registered. However, protection is not limited to businesses headquartered in the country of registration. Firms doing business internationally often register a trademark in multiple countries, sometimes very many countries. It is possible that "Le Cordon Bleu" was registered in Australia. (Indeed it turns out to be so registered, see below.)
Also, in some countries a trademark can be protected to a degree merely by use, without any registration. That is true in the US. I have not yet checked if it is true in Australia. If the plaintiff's mark was in actual use in Australia, that might be enough to get them a favorable trademark decision there. It will be Australian law that will be relevant here, not really international law.
It seems that the school "Le Cordon Bleu" objected to a restaurant called called "Gordon Bleu". That sounds to me similar enough that I think a US court might well award damages and/or issue an injunction, depending on the detailed facts, and the dates of usage (first usage usually wins).
The news story does not give the formal name of the case. Without the opinion or other case documents I cannot tell just what happened or on what legal basis in this specific case. I will search and update this answer if I find relevant information.
A search reveals that Le Cordon Bleu International B.V. owns several registrations in Australia to the trademark "Le Cordon Bleu" including:
- # 429369 for Class 8: Hand tools and implements (hand operated); cutlery, forks and spoons; side arms; razors
- # 429371 for Class 38: Communication; press agencies, radio, telegraph and telephone communications; teleprinting; transmission of messages and telegram
- # 429377 for Class 25: Clothing, footwear, headgear
- #429378 for Class 24: Textiles and textile goods, not included in other classes; bed and table covers
- # 429379 for Class 21: Household or kitchen utensils and containers ...
- # 429380 for Class 16: Paper, cardboard and goods made from these materials, not included in other classes; printed matters; bookbinding materials; photographs, stationery ...
- # 429381 for Class 9: Scientific, nautical, surveying, electric, photographic, cinematographic, optical, weighing, measuring, signalling, checking (supervision), life-saving and teaching apparatus and instruments ...
- # 485577 for a logo to be used on Class 29: Fresh meat, fresh fish, fresh poultry and fresh game; ...
- # 485579 for the same logo to be used on Class 31: Agricultural, horticultural and forestry products and grains
- # 485580 for the same logo to be used on Class 32: Mineral and aerated waters and other non-alcoholic drinks;...
and some 50 other registered marks for use of the words 'Le Cordon Bleu", the logo, or variants of these on various classes of goods and services. Most of these Australian trademark registrations seem to date from 1985 and are currently in force.
Thus there was nothing unusual in this case. A firm with a trademark (in fact 60 trade marks) registered in Australia for over 35 years objected to use in a related category of a confusingly similar mark, that seems to have been intended to play off the registered mark. This sounds like a routine trademark enforcement action.
Also. according to the Wikipedia article "Australian trade mark law" Australia supports "common-law use-based rights" as well as statutory rights under the Trade Marks Act 1995 (and previous acts). This means that in Australia, as in the US, a degree of protection can be obtained through use alone (in Australia), even without registration.