I dont know how to donate through the charity body you recommend, as it's in Arabic, and I dont know any Salafi charity organisations in English. Is it ok to build a masjid, if we don't know what aqeeda the imam will teach there?

Ustadh AbdulAziz al-Haqqan

For the charity, always choose those who are trustworthy, and it is easy now to translate the Arabic using AI. As for supporting a masjid, the same principle holds, choose what is trustworthy and known to be upon the Sunnah.