Well in that regard, the SSPX sold off their church in Syracuse to the muslims and now uses a diocesan church. 

Isn't there something in canon law that states when something ($) is donated for a specific purpose (e.g. windows) it MUST be used for that purpose only?  Or otherwise returned?

I also know in India that they use a diocesan church with the express permission of the local ordinary, at the very least in Chennai. There is a huge amount of ecuмenism in India. 

St. Peregrine SSPX Chapel in Cleveland ... same story.  They had a huge fundraising effort to  build a new church, and it brought in very large sums of money.  But no church was ever built.  They're still, ten years later, operating out of a dumpy little converted house.  It's likely that the money collected either directly from the parishioners or indirectly through their efforts was laundered for other purposes of the SSPX that did not directly benefit those who raised the money.

Beware of con artist contractors.  

you are absolutely right . There is substandard work all through our church .Bell tower , plumbing so bad you can hear toilets flush all the way up to the altar,  basement walls cracking,front door that has never worked right, unusable elevator .The list goes on and on but lets not forget in was the SSPX district hierarchy that made the changes to the original planned church and may and I say again MAY have forced the contractor to take the shortcuts and do the shoddy work to save money due to the enormous cost overruns After all the contractor is a parishioner and was at the time also the church accountant and financial advisor