Doubtful if the guide is the problem, it’s thread is in the form of a lug which leaves a gap when tightened.For the reverb, every bleed kit i’ve used seems to suck air in for fun, try not to create too much vacuum, and you can usually get by.Brakes, bleeding usually needs to be a lot more thorough, and takes a lot longer than the owners manual/tech videos would have you believe, also worth making sure your caliper is aligned perfectly(rotor dead centre of pad gap, pads perfectly flat to the rotor, and both hitting at exactly the same time), and your caliper pistons aren’t sticking, both can cause mushy lever feel/long lever travel.