I dont know if anything have changed. Maybe it has, so you can use longer names. When I started with Axoloti, back at the crowdfunding campaign, this was a limitation that we had to live with. So I kind of just stick with that rule. I havent really tried with longer names ever since, if they are accepted now.
Regarding the different sample rates. Well you will probably get sound of out it, as you do, but if the files are not converted to 16 bit 48khz(Axolotis format) and then converted to raw, then they will be played back at the wrong speed. Have you ever loaded a 48khz audio file into a 44,1khz project? You will get sound but it will play it back at the wrong speed and iMO be useless. And probably also not sound very good....
You should REALLY take your time and convert the files before using them in Axoloti. Again if you have a breakbeat 150bpm at 96khz and a breakbeat 150 bpm at 44.1... They will NOT match each others tempo.
Look at it like this: Most DAWs also only lets you use one sample rate in a project. So to make everything easier for yourself and to avoid other problems later on, it is good practice to convert them and use same sample rate as Axoloti