Regarding the validity of the short-term business visa in Australia, is the validity of multiple round trips a year counted from the date of issuance or from the date of first entry into Australia?

Generally speaking, Australian visas must not arrive after xxxxxxx (entry is not allowed after this date).

Your visa is multiple round trips a year, with a maximum stay of three months at a time. In that case, you must leave the country on September 30th.

Note that the last time you entered Australia cannot be later than the date on the visa, but you can stay for 3 months, even if your departure date is after the visa expires.

Of course, the validity period is from the date of issuance.