I think the difference between offering condolences and apologising is a fine, but important one.
To offer condolences is to say that you understand and empathise with the situation, and the losses that resulted. To apologise, is to say that you realise and admit that you were responsible, and that you are sorry for what has happened.
I think it is right to offer condolences, a reference to the passage of time, and to the fact that our two nations no longer share the hostilities that led to the deaths and destruction referred to.
But to offer an apology is to say that you think you are at fault for what happened, and that may not be behind the thinking that led to the condolence offer.
So the two approaches are different, and should be appreciated as such.
The British are a national of apologisers and thankers - think of that next time someone holds a door for you, and as you say thank-you, they say it as well (!).
So no, 'sorry' is not a difficult thing to say - but it must be appropriate to the situation, and be offered by the person(s) who has committed the act - and that criteria is not met here.