I think you are showing a lack of understanding about Ireland, Christinapple, when you write that 'the [sic] church over there has a lot more power [In NI and the Republic] than it does in Britain'.
There is not one church in Ireland, and there is a huge difference between churches in NI and in the Republic. The most obvious one is denomination - NI is [decreasingly] majority Protestant, the Republic majority [nominally] Catholic. Within that, there is a range of Protestant denominations, sects and groupings in NI, with a range of attitudes to social issues. In the Republic, the power of the Catholic church is hugely diminished - the church is seen as being at odds with current liberal social policy on matters such as transgenderism.
The idea that the catholic church has enough power to push the Nordic Model, or anything else, is decades out of date.
There could be a number of potential explanations for the low conviction rate for buying sex. There may be reasons similar to those for the low conviction rate in related crimes e.g. those 'buzz words' that irk you - rape and violence against women.
There would have to be detailed study to obtain the 'facts and evidence' both you and I value before jumping to the conclusion that it is the legislation, rather than its enforcement, which is at fault.
One obvious explanation is that prostitution is such a ubiquitous crime - there are hundreds of women, many of them trafficked into the country, forced to work in the brothels that exist all over Ireland, some of them are what are known as 'pop-up' brothels, which advertise their location, and then shut up shop and move on to another location. These are slick operations, and it must be very difficult to keep track of them and get evidence for a conviction.
But the fact that it's difficult to get a conviction doesn't mean that the police shouldn't enforce The Criminal Law (Sexual Offences) Act 2017 with the same vigour as any other law.
edited to remove those pesky asterisks that appear out of the blue!