Is it obligatory for non-residents to regularly attend the Arabic sermon being delivered? And does the presence of some local residents negate the condition of permanent residency mentioned in the fatwa? And is the former preacher sinful for this?

If the sermon is delivered in Arabic, it is not permissible to miss it or to hold another Friday prayer. The preacher should vary the sermon, but there is no evidence that prevents repeating the sermon or that obliges varying it. As for the condition of a specific number, the fatwa (definition) adopted by us is that no specific number is required for the validity of the Friday prayer; rather, the presence of what is customarily called a congregation is sufficient, as the Shari'ah did not specify a particular number.