Opposing the law of foreign countries and challenging court decisions in Russia and elsewhere, trying to change laws.
The initial reference you provide is in regard to changing municipal, Provincial or Canadian Law within Canada. Although W. G. H. & Associates is a Canadian law firm, the Canadian restriction on changing or opposing the law I expect, would not apply to laws in other countries unless that country also has restrictions in place.
That said, WT & JWs (through the law firm) seem to take pride in the changes made to laws within Canada which benefit WT/JWs, much of which is attributed to Glen How himself.
Perhaps WGH was (technically) not retained by WT but acting independently from WT when fighting for laws beneficial to WT/JWs (ie: JW freedom to preach and JW right to refuse blood), thereby not putting WT at risk in acting on those matters.