It's astonishing how anyone can peddle the same sort of nonsense that, in contemporary times, would be placed in the same arena as George Soros funding Antifa.
Alexander Helphand, also known as Parvus, was quite publicly disliked by a large majority of the socialist movement including the likes of Rosa Luxemburg due to his open German chauvanism and his twisting of theory in order to try and persuade the SPD into further supporting the war effort. Lenin showed him the door in Zurich and wrote encouraging other socialists to break from him. When Lenin and his companions organised to go via train through Germany, it wasn't Parvus who organised it but the Swiss socialist Fritz Platten and the Menshevik Julius Martov who proposed the idea in the first place - Lenin had wanted to get the British to allow them to travel via boat but had been refused. Parvus had many adventurous ideas and in 1916 tried to fund a failed strike movement in Russia as a way of disrupting the Russian war effort and it's true that up until the end of 1917 over 20 million marks went to revolutionaries in Russia of various stripes. The Bolsheviks, the Social Revolutionaries and the Mensheviks, as well as various other left-wing newspapers, all benefited from this money although it's telling that in April 1917 the Bolsheviks had to rely on donations from workers in Petrograd in order to raise the 75,000 rubles in order to purchase a print shop to get their message out to the workers.
Fursenberg, otherwise known as Yakov Ganetsky or his Polish name Jakub Hanecki, was a Bolshevik revolutionary involved in some of the same dodgy circles at Parvus and it's true that Lenin turned to him for funding whilst Ganetsky was in Stockholm. Ganetsky wired 2000 krona to Lenin in order to fund the travel for all the Bolsheviks in Zurich and he passed letters to and from Bolsheviks but ultimately he had very little influence of Lenin or the Party, acting only as a go-between. Lenin was in contact with Swedish Social Democrats through Gantetsky and he gave a speech at a meeting of the Left-Wing Swedish Social Democrats in Zurich and informed the editors of the 'Social-Demokraten' newspaper to trust the word of Alexandra Kollontai. It's clear to any observer of history that Europe in the early 1900's had a network of socialist organisations and individuals who assisted each other with open or clandestine methods.
This is a letter sent by Lenin to Ganetsky prior to arranging the train with the Germans: "Please let me know in greatest possible detail, first, whether the British Government will allow passage to Russia to me and a number of members of our Party, the R.S.D.L.P. (Central Committee), on the following conditions: (a) The Swiss socialist Fritz Platten receives permission from the British Government to conduct any number of persons through England irrespective of their political allegiances and their views on war and peace; (b) Platten alone answers both for the composition of the conducted groups and for maintaining proper order, and receives a railway coach for travelling through England, which he, Platten, is to keep locked. No one can enter this coach without the consent of Platten. This coach shall have exterritorial rights; (c) From a port in England Platten conveys the group by the steamer of any neutral country, with the right to notify
all countries of the sailing time of this special ship; (d) Railway fares shall be paid by Platten according to the tariff and the number of seats occupied; (e) The British Government undertakes not to place obstacles to the chartering and sailing of a special steamer with Russian political emigrants and not to detain the steamer in England, enabling the passage to be made in the quickest possible way.
Secondly, in the event of agreement, what guarantees can England give that these conditions will be observed, and whether she has any objection to these conditions being published.
If telegraphic inquiries have to be made in London we agree to bear the expenses of a telegram and a prepaid reply." -
https://www.marxists.org/archive/lenin/works/1917/mar/00jh.htm
It's clear to anyone that Lenin, and multiple other Russian socialists, were willing to accept help from any quarter and the idea that Lenin specifically was involved in German espionage is frankly ridiculous. Lenin here wants the British to convey him back to Russia, if that had taken place would you have considered him a British spy instead?