Did the whole of Europe gang up Britain when Britain took either Cape and Suez?
I think a quick history lesson on the Suez canal is in order. When it was built Britain's share of the canal was precisely 0%. It was a French and Egyptian canal. France was the majority shareholder with approx. 55%, Egypt had 40%, and the Ottoman government approx. 5%. Sadly for Egypt traffic was only about 20% of projections and they quickly fell behind on debt payments. Needing money to stave off bankruptcy they sold their shares to the British government who by the end of 1875; 5 years after the canal was finished; had 44% and was the single largest shareholder but still not the majority. The majority of shares remained in the hands of French investors.
In 1888 the canal zone was declared a neutral area under the protection of the British navy. This treaty came about as a result of the Anglo-Egyptian war where Britain seized physical control of the canal. It came about as a result of pressure from France, Ottomans, Austria, Russia, Germany, Spain and the Netherlands (so pretty much the whole of Europe) who made Britain guarantee passage to all vessels in war and peace (Article 1 of Treaty of Constantinople). The treaty was signed only with great reluctance by Britain who feared a coalition war against her if she didn't sign it.
So yes, I would expect Spain to help the Triunes to prevent a Roman takeover and I wouldn't be surprised if anyone with interests in the Far East joined as well. Whether they would be successful is another story. Rome could count on Ethiopia and as a result would have significantly shorter supply lines. Would it be enough to balance against the coalitions greater numbers I couldn't say.
TLDR of both comments....Britain had to contend with coalitions in acquiring both the Cape and Suez. One in war and one in diplomacy. Rome has already secured where the Suez canal will be; there will definitely be another 3 Johns meeting at the minimum and rapid declaration of war if Rome tries to seize the Cape.