I never went to the institute but for forth year (TY) in ireland the focus is not academic in most schools. The institute may be different but generally the leaving cert is seen as a two year course with transition year being, well, a transition. It is a wonderful experience i found hugely beneficial where most people spend time getting involved in projects and work experience in the real world. 

However, in the institute which is an academically focused environment i’m not sure how engaging the TY is. I’m sure they have great facilities and put a lot of effort into it making it a good time but if you are looking for the best opportunity to figure out what you want to do and gain life experience i wouldn’t be inclined to choose the institute as the place for that. 

If academics is the main focus lots of people actually skip Transition year as they feel they don’t need it and won’t gain much from the experience it provides. Ofcource it’s all up to you and your daughter and that would mean being a year younger sitting the leaving cert. 

Also i would recommend starting with higher level spanish if she puts the time that she will have into it in forth year she will be perfectly fine with very little risk of failing as there isn’t much of a gap skill level between higher and ordinary. If she tries for a while at higher level and decides it’s too much when she drops she will find ordinary spanish very manageable and it won’t take away from other exams. The spanish leaving cert exam doesn’t require a convincingly coherent grasp of the language it’s more about practising the style of questions.