I have an emonESP wifi interface on my emonTX, connected to my local network. So, data is directly sent from the emonTX to emoncms.org. Besides, data should reach my emonPI via the same local network (the 433 MHz ISM band radio is not able to reach the emonPI directly).
So the answers are no and yes 
I should add that data sent from the emonPI reaches correctly emoncms.org, so the problem is located in the link emonTX — emonPI.
In the emonHub log I can see messages like the following ones:
2021-09-28 14:26:26,017 DEBUG RFM2Pi Discarding RX frame 'unreliable content'? 27 70 45 3 80 235 183 62 249 188 3 250 223 174 247 199 142 58 44 223 100 (-85)
2021-09-28 14:26:26,129 DEBUG RFM2Pi Discarding RX frame 'unreliable content'? 30 71 253 191 112 125 95 22 67 165 63 127 236 231 239 127 127 179 207 150 90 (-85)
2021-09-28 14:26:28,263 DEBUG RFM2Pi Discarding RX frame 'unreliable content'? 10 93 61 252 125 168 132 239 237 255 55 200 109 100 125 254 27 24 192 25 241 (-85)
2021-09-28 14:26:29,021 DEBUG RFM2Pi Discarding RX frame 'unreliable content'? 21 121 247 30 209 190 9 214 205 81 186 245 128 129 132 203 122 118 30 214 101 (-84)
2021-09-28 14:26:31,015 DEBUG RFM2Pi 496038 NEW FRAME : OK 5 196 4 0 0 196 4 194 97 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (-0)
2021-09-28 14:26:31,019 DEBUG RFM2Pi 496038 Timestamp : 1632839191.02
2021-09-28 14:26:31,020 DEBUG RFM2Pi 496038 From Node : 5
2021-09-28 14:26:31,021 DEBUG RFM2Pi 496038 Values : [1138.26, 0, 1138.26, 233.49258, 25.8, 0, 0, 0, 0, 0, 0]
2021-09-28 14:26:31,022 DEBUG RFM2Pi 496038 Sent to channel(start)' : ToEmonCMS
2021-09-28 14:26:31,022 DEBUG RFM2Pi 496038 Sent to channel(end)' : ToEmonCMS
2021-09-28 14:26:31,131 DEBUG RFM2Pi Discarding RX frame 'unreliable content'? 25 151 253 68 81 249 237 25 145 97 203 188 49 45 222 126 212 27 110 18 253 (-85)
2021-09-28 14:26:31,213 DEBUG MQTT Publishing: emon/emonpi/power1 1138.26
2021-09-28 14:26:31,215 DEBUG MQTT Publishing: emon/emonpi/power2 0
2021-09-28 14:26:31,217 DEBUG MQTT Publishing: emon/emonpi/power1pluspower2 1138.26
2021-09-28 14:26:31,219 DEBUG MQTT Publishing: emon/emonpi/vrms 233.49258
2021-09-28 14:26:31,221 DEBUG MQTT Publishing: emon/emonpi/t1 25.8
2021-09-28 14:26:31,223 DEBUG MQTT Publishing: emon/emonpi/t2 0
2021-09-28 14:26:31,224 DEBUG MQTT Publishing: emon/emonpi/t3 0
2021-09-28 14:26:31,226 DEBUG MQTT Publishing: emon/emonpi/t4 0
2021-09-28 14:26:31,228 DEBUG MQTT Publishing: emon/emonpi/t5 0
2021-09-28 14:26:31,229 DEBUG MQTT Publishing: emon/emonpi/t6 0
2021-09-28 14:26:31,231 DEBUG MQTT Publishing: emon/emonpi/pulsecount 0
2021-09-28 14:26:31,233 INFO MQTT Publishing: emonhub/rx/5/values 1138.26,0,1138.26,233.49258,25.8,0,0,0,0,0,0
2021-09-28 14:26:35,883 DEBUG RFM2Pi 496039 NEW FRAME : OK 5 143 4 0 0 143 4 190 97 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (-0)
2021-09-28 14:26:35,887 DEBUG RFM2Pi 496039 Timestamp : 1632839195.88
2021-09-28 14:26:35,888 DEBUG RFM2Pi 496039 From Node : 5
2021-09-28 14:26:35,889 DEBUG RFM2Pi 496039 Values : [1088.8110000000001, 0, 1088.8110000000001, 233.45525999999998, 25.8, 0, 0, 0, 0, 0, 0]
2021-09-28 14:26:35,890 DEBUG RFM2Pi 496039 Sent to channel(start)' : ToEmonCMS
2021-09-28 14:26:35,890 DEBUG RFM2Pi 496039 Sent to channel(end)' : ToEmonCMS
2021-09-28 14:26:35,978 DEBUG MQTT Publishing: emon/emonpi/power1 1088.811
2021-09-28 14:26:35,980 DEBUG MQTT Publishing: emon/emonpi/power2 0
2021-09-28 14:26:35,982 DEBUG MQTT Publishing: emon/emonpi/power1pluspower2 1088.811
2021-09-28 14:26:35,984 DEBUG MQTT Publishing: emon/emonpi/vrms 233.45526
2021-09-28 14:26:35,985 DEBUG MQTT Publishing: emon/emonpi/t1 25.8
2021-09-28 14:26:35,987 DEBUG MQTT Publishing: emon/emonpi/t2 0
2021-09-28 14:26:35,989 DEBUG MQTT Publishing: emon/emonpi/t3 0
2021-09-28 14:26:35,990 DEBUG MQTT Publishing: emon/emonpi/t4 0
2021-09-28 14:26:35,992 DEBUG MQTT Publishing: emon/emonpi/t5 0
2021-09-28 14:26:35,994 DEBUG MQTT Publishing: emon/emonpi/t6 0
2021-09-28 14:26:35,996 DEBUG MQTT Publishing: emon/emonpi/pulsecount 0
2021-09-28 14:26:35,998 INFO MQTT Publishing: emonhub/rx/5/values 1088.811,0,1088.811,233.45526,25.8,0,0,0,0,0,0
2021-09-28 14:26:36,840 DEBUG RFM2Pi Discarding RX frame 'unreliable content'? 31 125 153 124 155 107 135 203 185 233 62 117 237 222 10 251 128 241 31 137 226 (-85)
The “unreliable content” lines are suspect…