What are the festivals that one can celebrate during an asauca period? Our priest had told us we can celebrate the festivals that are meant for God and avoid all festivals that are celebrated for us; can we celebrate Thiruvadipooram with offerings for Thayar or should we not celebrate any festival at all?

In general, no festivals should be celebrated for a year during the period of taint. But one has to cook and offer food for Perumal during that period irrespective of a festival. It is a tradition that sweets are not prepared and festivals are not celebrated for a year with the exception of Azhwar and Acarya thirunakshatram.
NOTES
Sweets can be prepared and offered to Perumal during Azhwar and Acarya’s thirunakshatram.