Why not just take an anion exchange resin, stir in KF or NaF in methanol, wash the heck out of it again with clean methanol, dry it, then stir your compound for several hours over this resin. Filter off resin and rinse, rotovap down and voila pure product. Make sure to use a notable excess of resin eqs (like 2) since it will be slower than liquid phase. No need to mess around with TBAF.
I saw you were doing something with resin, but I didn't really follow and it seemed painful.
OR! Do it biphasic. KF in water, product in organic phase, then stir the christ out of it. Use saturated KF because the high salt concentration should force the organic products to stay in the organic phase since I saw your substrate is rather hydrophilic. I know MeCN and sat KFHF in water are not miscible, that's how I made sulfonyl fluorides out of sulfonyl chlorides. If that solution can keep MeCN out of the water phase, then I bet it will force your product to stay in the organic phase, MeCN is freely miscible with pure water.