Dear Punjabi munda bro you are dealing with the incident of Miraj / Spiritual & physical ascension of Prophet PBUH, which is highly c0omplex and mystical affair that could not be decoded in absolute literal or metaphorical sense till this day.
You can consult exegetes, theologians, experts of Hadith material, spiritualists or even the doctors of jurisprudence in order to collect some vital fragments of this significant incident of the exalted Prophet PBUH but the whole picture of it could not be able to shape up that easily my friend.
Let me give you some clues about Trees and rivers and what symbolical significance they usually carry in mythologies of ancient civilizations in brief terms;
Tree: For some experts it carries different meanings for different constructs of religion, mysticism, legends and mythologies. The most common meaning of the symbol of tree is an ‘Occult / Hidden Knowledge’.
Its roots symbolize the need to derive nutrients of knowledge and understanding of religion by an adherent in order to start the process of illumination. The canopy of its branches and leaves alludes to the perfect attuning of Man with its immediate environment and age in order to stay relevant and vital. The main trunk symbolizes the urge of retaining inner strength and resolve on the face of any adversity from its environment in order to sustain and derive spiritual benefits.
Rivers contain water and in religious terms it speaks about a vital force of divinity to purify and cleanse the inherent and physical impurities of an individual for centuries. In this Hadith which you have quoted the possible meaning of the two hidden rivers of Lote Tree might signify the vital streams of heavens / divine revelation / illumination that could remove every tiny bit of uncertainty and doubt in the heart and mind of a believer.
The two obvious ones of Nile and Euphrates might allude to the streams of those lands where Prophet Moses and a line of Judaic apostles appeared for the Jewish community in the beginning to enlighten them so that they could carry the torch of guidance for the rest of humanity. Euphrates River belongs to the ancient lands of Mesopotamia where legendary arch Prophet Ibrahim was born, raised and carried many years of his prophetic mission before being exiled by its inhabitants. His (Prophet Ibrahim AS) monotheistic strain of message then recurred centuries later through the efforts of the adherents of last Prophet of mankind PBUH in that same land and hence will keep on its duty to purify the souls and quenching the thirst of divine knowledge of humanity till the world meet its final destination of violent revolution and destruction.