Q: How should I reply to the editor if my manuscript has been accepted after a second revision but under condition?

Firstly, congrats on your paper getting accepted, that too for a special issue! That makes it even more commendable.

So, coming to your query, based on what you have mentioned, this doesn’t seem a conditional or provisional acceptance, but an outright one. :-) The comment by the editor (on your comment around non-performing loans and volatility) is more like a ‘nice to have’ rather than a ‘need to have.’ As you have said, you explained this to the reviewers, but the editor may have missed this. Also, as this is a special issue, the response was probably by a guest editor designated only for this issue and who may not be privy to or involved in all the communication. So, you could write to them saying that you have already mentioned this to the reviewers and that you have really have nothing more to add – basically, just what you told us. Of course, you’ll probably start (and end) with a note of thanks for the acceptance. :-)

That being done, you may then wish to turn your attention to the last action you need to do before publication: proofing. For that, you may find these resources helpful:

• What is the minimum number of comments to be included while proofing my paper?
• Can I correct an error in citation at the page proof stage?
• Can I replace an image at the proofing stage before publication?

Hope that helps. All the best in taking the accepted paper smoothly toward publication! And again, congrats on the acceptance!!