tempi
Most English dictionaries give two forms for the plural 'tempo' as tempos or tempi.
tempo
tempo
The plural form of apparatus is apparatuses. It has no foreign plural.
Forum---Plural Form Forums,Foreign Plural Form Forumina
The foreign plural of "prospectus" is "prospectuses."
The foreign plural of addendum is "addenda."
Well, the English Plural is momentums and the Foreign Plural is momenta!
Stimuli is already the plural of stimulus.
The foreign plural for cranium is "crania."
The foreign plural of "madame" is "mesdames."
The foreign plural of criterion is "criteria."