Is it acceptable to offer Salah/Taraweeh in an online Jamaat in the present situation of lockdown?

The answer to your question is YES. Online Salah/Taraweeh is acceptable in the current unusual circumstances of lockdown where people are not allowed to go to the Mosque.

There are two valid reasons to support the above the above answer:

1) According to Imam Malik's point of view, you are allowed to offer Salah behind an Imam even if there is a river or a road in between you and the Imam (or the other rows of congregation). Even though one is not able to see the Imam, yet his Salah will be accepted. Given this condition it is obvious, that it is acceptable for the Imam and you to be separated by long distance, provided that you are able to hear the Imam and follow him.

2) There is another question which comes up in mind that what should one do if network goes off while you are praying online. We have already come across a similar situation in our daily lives. If the loudspeaker stops abruptly while a Namaz (Salah) is ongoing, then the follwers who are not able to hear the Imam are supposed to continue their own namaz and complete it. Similarly, if your network goes off while offering online Salah you are required to complete your remaining namaz (Namaz) on your own.

The same Fatwah has been also approved by Shaikh Mohammad Hasan Dadu who is a knowledgable Muslim Scholar, author, writer, faqeeh, and poet from Mauritania.

Conclusion: Hence in extreme situations like Lockdown, it is acceptable to offer Salah/Tarweeh online behind an Imam of your time zone.