It is very very unlikely that IB+ will status match a BAEC elite member.

There isn't a whole lof of benefit to having status with IB+ instead of with BAEC. The parking benefit is obviously a major one, though. But if you never drive to Barajas it's worthless to you. It would make more sense, therefore, to keep working towards lifetime Gold with BA.

If you can stretch to the 6250 Elite Points, however, 2 years of Platinum status (instead of 1 BA year) can be quite relevant.

You also need to take a very close look at your travel patterns and whether you would actually earn IB+ status from it. The same IB economy flight might get you 10 Tier Points but only 25 IB Elite Points...

FWIW I've been in Spain for quite awhile myself, but it would never occur to me to aim for IB+ status instead of BAEC...