Your English is good!
I'd think that what was happening with certain Leons will not happen with
Ibiza, I knew someone, that had a Leon 2 or 3 and he ended up with ignition problems, he booked his car into his local family owned SEAT garage only a few months after getting FOC work done on the cam chain area (1.2TSI 8V), only to find that there was a modification that SEAT had brought out to stop water flooding onto the ignition twin coil assembly - so they were authorised to carry out that work. SEAT would not pay for the now failed/faulty twin coil assembly or the corroded plug leads, which he, and I thought was completely wrong. Surely if SEAT accepted that the "cause" of this failure was their design error, then the resulting failures were "effect" and as these effects permanently damaged some parts, they should have been replaced FOC while applying this corrective modification.
Back to the topic! As TDI cars get this sound proofing, I'd think that it will be okay for your 1.4 16V, leaving it out would just be a way to save money at this end of the
Ibiza range.