Most likely not, next event will probably have some other set of berries for whatever Indrik comes next.

We don't know.

Last year there were 4 evolved indriks available, but the berries for each one were only available in one quarter (dawnwood in Q1, luminous in Q2, onyx in Q3 and pure snow in Q4). Then all 4 were available during the New Life festival but we don't know if that was a planned addition or because they had so many problems with running the events and ended up rearranging the schedule they brought them back to allow for people who missed it or ended up with excess tickets due to cancelled events and tickets being included in New Life.

Other than that no berries have come back after the initial release period and it's not been possible to make the indriks any other way. But since the whole system of tickets, feathers, berries and indriks was only introduced at the end of 2018 and a year long cycle was planned it's still relatively new and there hasn't really been many opportunities to bring them back. It's also hard to tell based on other items because those have been so inconsistent, some things come back regularly, others are available once and never again and some return but in different formats. (Like the blacksmith's costume which was in the crown store, was removed for years and is now in crates.)

It might be that at some point previous indriks/berries are available again, either instead of new ones or alongside them. Or it might be that each one is only available once and then never again.

If you really want the spectral indrik and want to make absolutely sure you're able to get it the only option is to buy tickets with crowns, but that will be expensive. If you don't want to do that all we can say is wait and see, they might come back but it might be months or years before that happens and might be via an entirely different system.

@Danikat Thanks for the detailed information on this. It didn't dawn on me that the berries were in limited supply (only available during certain periods).