The problem has been temporarily resolved. Here is the feedback I got from CrowdIn, who have been very gracious and sorted it out very quickly.
Even for Open Source projects there is a default strings quota - 5000, usually it’s quite enough. After the recent update, your project contain 5050 strings and project was suspended automatically due to exceeded quota.
Your quota was increased to 6000 strings, so you can continue translations. If you will need to maintain more strings, just let us know and we will gladly help you."
In appreciation of the increased quota, we should help fix this from our end too. We need to look at trimming some of the old strings from the translations, and probably remove some of the abandoned languages too.
Many thanks to the staff at CrowdIn.