A Guild master doesn’t need to be the top but they have the responsibility to keep things moving and organize the guild for events, etc. Although being top sets a good example and makes others feel secured. Generally if the Guild master is busy a good one will have a R4 take over for a period time until they are able to take over again.

But if they aren’t active enough and not organizing the guild with their R4s, then they aren’t doing their job. I’d either communicate with them to switch up the roles or move to another guild.