The 'congratulations' group
These nouns refer to things that are said or written. (Pleadings, promptings, recriminations, and vituperations also occur in a singular form with no determiner.)
acknowledgements advances apologies blandishments commiserations compliments condolences confessions congratulations directions instructions memoirs murmurings noises pieties plaudits pleadings promptings ramblings ravings recriminations regards sophistries sweet nothings thanks tidings vituperations vocals words writings
So congratulations are due to all involved, especially the teachers and students who were absolutely wonderful.
Their philosophical ramblings take place within earshot of the waitress.
Her words deserve careful interpretation.