A few points:
Firstly, a word from my insurers - and I apologise in advance if this sounds very boring - but I want to make it crystal clear that no statements made by or attributable to me on this forum should ever be construed as professional advice or a professional opinion. For the avoidance of doubt, any views expressed by me are entirely personal in nature and do not represent and should not be construed as constituting legal or professional advice of any nature whatsoever.
Having got that out of the way, I would point out that no lender would have any role in initiating any criminal prosecution under the statutory provision under discussion. A lender may, in theory, be in a position to ground a civil action in tort (e.g. for fraudulent misrepresentation) but that risk is probably more theoretical than real in the context of the OP's circumstances.
If you are asking me if I think it is likely or probable that the DPP would exercise her discretion to initiate a prosecution in circumstances where she was on notice that a potential borrower misrepresented the source of a sum of money in the context of a loan application - then the truth is I really don't know. If you are asking me whether I think such a prosecution is possible then the answer is absolutely yes.
The DPP has already brought prosecutions under this legislative provision in the the context of residential mortgages (admittedly in relatively high value cases) and a sizeable portion of the defence bar in the US has been gainfully employed since the onset of the financial crisis in the defence of so-called "liar loan" cases brought by local prosecutors in the US. Who is to say that our DPP won't take her lead from her US counterparts in this regard?
I would point out that a material contributor to the financial crisis, both in Ireland and elsewhere, related to the fact that many borrowers embellished (to put it politely) their income and/or assets in loan applications. To the extent that such behaviour is increasingly seen as unacceptable socially and/or politically, then my sense is that, yes, it is increasingly likely that we will see prosecutions for relatively minor deceptions. Ultimately such actions have a cumulative societal impact, which is surely in all our interests to censure.
Leaving aside the possible legal implications for a minute, is anybody seriously taking the view that the OP should consciously and deliberately lie to his lenders about the source of a financial asset? Taking a step back for a moment, does anybody really think that is sound advice?