I do not see many European banks wanting to get involved in the Irish mortgage market at all? Most profitable European banks keep a very small mortgage portfolio even in their home country and the large institutional shareholders frown on banks who hold large portfolios! DB is in the process of trying to dispose of it's interest in the German market (valued an €146b) for two reasons it is unprofitable in comparison to the traditional banking businesses of asset management & investment banking and because their shareholders have indicated that they should. In fact at least three of their major institutional shareholders have indicated that they should divest themselves of their entire retail division! For most of the major European banks retail banking is not a very profitable business and the less of it you do the more profitable you are.
Even in an area such as Basel where a large percentage of the work force lives in Germany or France, you will be hard pressed to find even a single bank willing to consider doing a cross border mortgage. In this case the legal structure is very similar as the law in all three is based on civil law and the Napoleonic codes, language is not an issue and most workers are high income earners as the are based at the HQ of large MNCs.