You are there to observe, report and guide if asked. You are not there to direct or control. As an Observer you should be aware that different countries have different customs, cultural background, behavioral rules. etc Have the latest version of the competition handbook available on your mobile device? If you are a paper- worker, you should have a printout of the handbook with you. Useful links
Handbook: https://www.veteransfencing.eu/wp-content/uploads/2021/07/EVF-Circuit-Guidelines- 2022. pdf
Rankings: https://www.veteransfencing.eu/fencing/rankings
Rules: http://fie.org/fie/documents/rules
Equipment: http://fie.org/fie/documents/equipment